Reinstall Windows over your current system

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Article ID: 835829
The articles set out below are articles created and/or produced by Future Publishing Limited. Microsoft is not responsible for the content, accuracy or opinions expressed in these articles.
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Got a problem? This is your first stop. It?s not as comprehensive as a full reinstall, but it is much quicker and could solve your problem with the least amount of hassle


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Before you start looking at reinstalling Windows you need to back up your important data ? just in case anything goes horribly wrong.

When was the last time you backed up your data? If your system went down right now how, much work would you lose? No one ever does it often enough. Backing up your data is not something that will fill you with joy. In fact the very nature of backing up data is perverse ? as you never really want to rely on that backup, because it generally means that something has gone wrong with your system.

The good news is that this is a backup with a difference and it is something that, if you do right, you can refer back to at a later date. You see the thing about this backup is that you are going to use it again straight away? well, right after you?ve reinstalled Windows anyway.

Prepare to lose everything

The big question is what you should back up and what you should leave. The golden rule is to only back up data files that you need. That?s data files, not utilities, applications and programs ? you should reinstall these from your original discs after you?ve reinstalled Windows. That way you won?t have problems with Registry entries either. So, programs are out then.

What data files? Ideally any that will be of use or that you need. If you just backed up every file you ever created you would find some completely useless stuff. Before you back up, have a good root around your hard drive to find anything you?ve created. The My Documents folder is usually a good place to start, but some programs will throw files all over the place.

You should also take this moment as an opportunity to sort out your e-mails, Web bookmarks and address books. You can take your e-mails with you if you organise them first, but only if you trim them down a bit.

If you are going to do this, then make sure than your e-mail program can import your e-mails once you?ve exported them (try it to make sure). Later on we?ll talk about how to structure your hard drive to make this easier next time.

How to back up your system

If you only have access to floppy disks then you are going to be limited to your most important files only. If you have something bigger like a CD-R or Zip drive then you should be able to back up everything you have ever created quite easily.

Once you know what you want to back up you can start work ? first, run Microsoft Backup. You should find it under Program Files, Accessories, System Tools in the Start menu. If it?s not there, you need to install it from your Windows CD.

When you start Microsoft Backup you are presented with this screen. From here you decide which files you want to back up.

You select files by clicking on the boxes next to files and folders. Remember that you don?t have to back everything up, so be selective.

By clicking the Next button you move on to selecting where you want to put those files ? if you have a backup device select this now.

Clicking Start Backup will, obviously, start your backup. This can be quite slow, so give yourself loads of time.


A lot of the problems that will eventually lead to you reinstalling Windows are caused by software developers mucking around with key files. If the files that Windows needs aren?t there then there?s not a lot you can do apart from reinstalling on top of your current system.

This is a slightly different process to reinstalling from scratch on a clean hard drive, because you actually keep all the data and settings that are already there. You?re also delaying the inevitable if you haven?t formatted for a while, as this method won?t clear out any redundant files or solve any conflicts with drivers. The good news is that it is usually easier to do and should mean that your system is up and running again in next to no time.

How bad is bad

The first stage in reinstalling Windows is to work out how bad a shape your machine is in. If you can?t even get into Windows without it crashing then you are going to have to reinstall from the DOS prompt. If you can get into Windows okay, then you should be able to reinstall this way, provided that you can either see your CD drive or because you?ve copied the installation files on to your hard drive already. If not then you are going to have to reinstall from DOS.

Either way you should understand the principle of what you are about to do. At the moment your machine is not working properly because one or more essential files have either been overwritten by incompatible versions or have been deleted.

By reinstalling Windows on top of your current installation any missing files will be replaced and you should be prompted for any files that already exist with different dates (see below).

Reinstalling from Windows

If you are able to get into Windows then you should start off by putting your Windows CD into your CD-ROM drive. Close down the automatic pop-up screen that appears when the disk autoruns and then open Windows Explorer. Point explorer at your CD-ROM drive and in the root of the drive you will find a file called SETUP.EXE. Double-clicking this file will start the installation of Windows. Skip to ?The reinstallation procedure?, below.

Reinstalling from DOS

If you can?t get into Windows then you are going to need to use your boot disk to see your CD-ROM drive. You should have a boot disk already ? if not then you should elsewhere in this article for information on creating one. Once you have this disk you should boot your computer with it in your floppy drive and restart your PC. Once the disk has booted, put the Windows CD in the CD-ROM drive, switch to the relevant drive (by typing the letter of the drive followed by a colon, such as D: or E:, and pressing [Return]) and then type SETUP.EXE and hit [Return]. Windows will now start reinstalling itself.

The reinstallation procedure

During installation, if Windows finds a system file newer than its own replacement, it will offer you the choice of keeping the newer file. Make sure you answer Yes to this question.

If Windows still refuses to work after this, you need to repeat the procedure for reinstallation, but this time answer No to the above question when asked. This should give you a fully working Windows installation ? you might encounter problems with individual applications, but if this is the case, all you have to do is reinstall that application.

How to create a boot disk

If at some stage Windows won?t boot, you?ll need a boot disk. And you?ll need to make one. This is how:

What happens when you try to reinstall Windows over the top of an existing installation, but it makes no difference? You?re going to have to reformat your hard drive and reinstall Windows from scratch, that?s what. Take a minute to think what this means ? a formatted hard drive is blank. That means no Windows and no DOS, and nothing to tell your computer that you?ve got a CD-ROM drive connected, or how to use it. If you?re going to reinstall Windows from a CD-ROM this presents a real problem, which is why you need a boot disk.

A boot disk is designed to bridge the gap between a blank hard drive and your CD-ROM drive. It should contain DOS drivers for your CD-ROM so you can use the CD to install Windows. To use it you simply put the boot disk into your floppy drive and turn on your computer. Provided your BIOS is set to boot from the floppy drive before your hard drive (most are), your computer will boot into DOS and your CD-ROM drive will be accessible.

Once you?ve reformatted your hard drive you can think of the boot disk as your last tenuous link to a working PC ? and this is not exaggerating either, so don?t lose it (in fact, we?d recommend you back up your boot disk once you?ve created it!).

How to create a boot disk

You create your boot disk in Windows, but before we show you how let?s get a formality out of the way: First, Microsoft likes to call boot disks ?Windows Startup Disks?. Both names are interchangeable, so don?t let that confuse you.

Creating a Windows 98 boot disk

To create a Windows 98 boot disk, simply pop a blank floppy into the drive and go through the boot-disk creation procedure. To do this, open the Control Panel and open Add/Remove Programs. Switch to the Startup Disk tab and click Create Disk? The correct CD-ROM drivers are put on the floppy for you, there?s no fiddling around and no need to add extra files.

How to create a boot disk if you can?t get into Windows

It?s easy to create a boot disk in Windows, but if you can?t get in then it?s still possible, just a little harder. We show you how to do it:

Boot into DOS (press [F8] on startup to bring up the boot menu). Put a floppy in your drive and type format a: /s. This will create a bootable floppy disk. The next stage is the crunch point ? you need to find the system-configuration file for your CD-ROM drive and copy it to your floppy disk.

This file will have come with your system, or ? if you?ve upgraded your CD-ROM drive ? will have come with the drive itself. You need to find and copy the file that has a .SYS extension from this disk to your hard drive, then copy it from there on to your boot disk.

Next you need to copy the Microsoft CD extension on to the floppy disk. Enter COPY C:\WINDOWS\ COMMAND\MSCDEX.EXE A: and hit [Return]. If this file isn?t there, it?s corrupted, so you need to find it. To do this in DOS you should type DIR /S MSCDEX.EXE, to search your drive. Once you find it, copy it on to your boot disk.

Next, make your floppy recognise the CD drive when it boots by creating CONFIG.SYS and AUTOEXEC.BAT. In DOS type A: to take you to the floppy drive. Next, type EDIT CONFIG.SYS. Type in device=< 'drivername'>.sys /D:mscd001, where 'driver name' is the name of the .SYS file from step two.

Save your CONFIG.SYS file. Next we need to create the AUTOEXEC.BAT file. Create that file by typing EDIT AUTOEXEC.BAT. Once this file comes up you should type MSCDEX.EXE /d:mscd001. Save the changes out to your disk.

The final stage is the simplest of all. Just re-boot your machine with the floppy disk in the drive and you will find that you are back in DOS and can see your CD drive.

How to partition and format your hard drive

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Before you can reinstall Windows, it?s a good idea to set up your drive and format it. We show you the best way for your machine.

Hard drives are now pretty big beasts. Even cheap machines now ship with an average hard drive of 4Gb, and you may have this size or bigger. The problem is that this amount of data needs organising or it will soon degenerate into an unseemly mess. The best way to do this is to partition your hard drive into smaller sections, each acting as a virtual hard drive in its own right.

One way of splitting your hard drive is simply to partition it in two: your first partition is your system drive, which has Windows and your program files on, and the second one is reserved for all your data files. The size you give to this setup is dependent on the size of your hard drive and what sort of data files you handle. If you edit large graphics or sound files regularly then you probably want to go for a 50-50 split, otherwise you should settle for a 60- 40 split, with the system space getting the lion?s share. Therefore, if you have a 4Gb hard drive and you don?t play around with large files particularly, you should aim for around 2.4Gb for the system partition and 1.6Gb for the data one.

An alternative way is to partition your hard drive into three, adding a backup partition to your system and data ones. This is particularly useful if you work on your machine or you have a lot of data that you have spent a lot of time creating.

Due to space limits this is usually only worth setting up if you have a bigger hard drive (say 6Gb or more). If this is of interest to you then you should aim for a 50-30-20 split, with the 20 per cent going to your backup space, 30 per cent to data and 50 per cent to the main system area. On a 6Gb drive this would equate to 3Gb system, 2Gb data and 1Gb backup.

Final thoughts

Below you will find the method for actually partitioning your drive. It?s worth noting that before you begin going through these steps, everything on your hard drive will be lost once you change the size of a partition. So make sure that you?ve successfully tested your bootable disk before you start.

FDISK creates two kinds of partition ? Primary contains the system or boot drive only, while Extended contains all the other drives, which are created as ?logical? drives within the Extended partition.

To format your newly partitioned drives you should re-boot off the floppy you created earlier and then do a full unconditional format on each partition. The format for this is FORMAT *any switches* *drive letter*:. The only switch we are interested in is the unconditional one, which is /U. So, to format your main drive you should type in FORMAT /U C:. If you created three partitions then you would have to also do D: and E:.

How to create partitions in DOS

FDISK is a powerful utility, and relatively straightforward to use. Remember that you?ll lose all your data as soon as you create a new set of partitions, and you?re away?

Boot from your floppy disk and make sure you can see your CD-ROM drive, as you are about to leave your old setup. Once happy, type FDISK to start Microsoft?s partitioning program.

After answering yes to the question of FAT32, you should select the fourth option to see what your current hard drive setup is. Here we have two partitions, so the first task is to delete them all.

Select option 3 to delete partitions and delete everything. Once you?ve done that you can create your partitions again. Select option 1 and then 1 again to create the primary partition to the size you specify.

The next step is to create your extended partition. Select option 1 followed by option 2 to start creating this second area. When prompted you should make the extended partition use all the space left.

The last step doesn?t actually create any logical partitions ? you have to create these yourself in the extended partition. FDISK will automatically prompt you for the first one, just set it as big as you want.

Finally you should check that all the partitions are set up as you want them by selecting option 4 from the main menu again. Once happy with your setup you need to re-boot and then format your drives.


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You?ve done your preparation, your files are backed up and your boot disk is ready. Now?s the time to actually reinstall Windows from scratch, so here goes?

Your hard drive is freshly formatted and you?ve got your boot disk ready ? it?s time to reinstall Windows.

All versions of Windows have slightly different setup screens so the following walkthrough is just a guide ? some of the screens might not appear on your version of Windows and some might appear in different order.

What you need
- 45 minutes of free time.
- Your Windows Product Key.
- Another blank floppy disk.

Don?t forget!

If you think you?ve answered something wrong during the setup you can always hit the Back key and change your mind. As long as you haven?t started copying files you can always click Cancel to quit.

First, insert your boot disk, switch on and ensure your PC is set up to boot from the floppy drive ? if it isn?t, enter your BIOS, select your floppy drive as the first bootable drive, and save your changes and exit. You should be presented with a menu. Choose the option to start with CD-ROM support.

Put the Windows 98 CD into the CD drive and type its drive letter followed by a colon (for example, D:) and press [Return]. Then type SETUP [Return] to start the Windows installation procedure.

The first thing that happens during the install is that Setup performs a routine check on your system. Press [Return] and ScanDisk checks your drive, after which the system registry is scanned. You must allow it to fix any errors it finds on the drive before you can continue. Now you?re ready to begin Windows Setup proper, which should take between 30 and 60 minutes.

The first choice you have to make is to decide the directory you want to install Windows into. While the setup program gives you the choice of installing to a folder that isn?t called Windows we recommend you don?t change the name. To guarantee all your programs work properly you should install to C:\Windows.

Next you choose your set-up options. ?Typical? is the normal choice, ?Portable? is for installing Windows on a laptop, ?Compact? saves disk space by not installing optional components and ?Custom? is ideally for advanced users. We?d recommend you choose Typical.

The final two choices are your Windows Components and geographical location. We?d recommend you choose the standard components, since you can always add and remove others later via the Add/Remove Programs Control Panel. For location choose the country you?re in.

Now you?ve chosen all your options, Setup decides it?s a good time to make a new Startup Disk. Put a fresh floppy in the drive and click OK. Don?t use your original boot disk ? it?s a good idea to keep a copy of that just in case.

After your startup disk has been created there?s a slight pause ? eventually a ?Sit back and relax?? screen will appear as Windows installs. The progress of the installation is indicated by a progress bar on the bottom left of the screen. After the installation has finished you?re ready to restart and use your new installation of Windows for the first time. Make sure you remove the boot disk before clicking OK.

Now you?ve only got a few more settings to tweak. First, enter some user information. Next you need to read and accept the licence agreement, then enter your 25-character Product Key (the dashes are added automatically).

During the next stage of the installation Windows installs software drivers for any plug-and-play devices you have attached to your system. After that, various Control-Panel settings are decided. You need to choose your geographical location in the Date and Time Properties dialog box.

Next you need to reinstall your monitor drivers. The Add New Hardware wizard will appear and try to locate drivers for your monitor. If you?ve got them on CD or floppy then put the disk in now and select Let Windows Search for Drivers. If you haven?t got any handy then you can choose Display a list of drivers in a specific location. Choose the default plug-and-play monitor.

The default monitor will get you into Windows, but limit you to 640x480 screen size with 16 colours. Once you?ve installed your monitor driver, install your graphics-card drivers. That?s it, Windows is reinstalled! Now it?s time to turn to move on into the post-install phase?

Post install

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You?ve reinstalled Windows, but there are still a few things to check before you can be confident you?ve got a working system.

Finally, your installation is complete and you?ve got a working version of Windows. A quick look at your Windows folder will probably reveal it?s about half the size it used to be, which means your PC is not only going to run faster, but it will no doubt crash less often due to a reduced number of system file conflicts.

Before you get too excited, however, now is a good time to take a few moments to check that Windows has recognised all your hardware correctly. The Windows hardware-detection routine in the setup process is hardly fail-safe, and it will quite happily ignore some of your hardware devices. In our experience SCSI cards and removable storage devices are the most likely things to go wayward.

Finalising hardware settings

To find out exactly what Windows thinks you?ve got installed, right-click on the My Computer icon and choose Properties. This will bring up the System Properties dialog box. Switch to the Device Manager tab and have a look to see if all your hardware is listed.

If a device has a yellow triangle with an exclamation mark next to it then it?s got a problem. Highlight the device and click Properties to get more information about what?s wrong. It?s usually the case that reinstalling the software drivers from your backups will solve the problem. Occasionally, if Windows is being really stubborn, you might need to remove the device from your hardware profile altogether and reinstall it through the Add New Hardware Control Panel before it starts to work.

If there?s no mention of a piece of hardware you know you?ve got attached to your system in Device Manager (and it doesn?t work) then you?re going to have to prompt Windows to search for it. You need to use the Add New Hardware utility in Control Panel. Load it up and click Next twice. After a bit of hard-drive grinding, Windows will ? hopefully ? detect your missing device and install the drivers.

If it draws a blank then you?re going to have to do things the hard way. Click Next again and Windows will try and locate hardware that is not plug-and-play compatible. If it still draws a blank you?ll be asked if you?d like to select your device manually. Select your type of device from the list available and Windows should detect it. If you can?t spot the type of hardware device you want to install in the list then choose Other ? surprisingly most things seem to be in there.

It?s all over

It?s been a long hard slog, but you?ve finally got there. Well done, you now have a fresh installation of Windows. Unfortunately, you?re now faced with the dubious pleasure of installing all your programs and copying your data back on to your hard drive, but at least you?ve given your PC a good detox.

Once you?ve set your system up you might like to consider creating a drive image. This is a copy of your hard drive with the fresh Windows installation on it. Next time you want to reinstall Windows you simply copy this back on to your C: drive ? this gets the job done in half the time and without the worry of setting it all up again.

Reinstalling your hardware

Run Add New Hardware from the Control Panel and Windows searches for plug-and-play devices that aren?t properly installed, producing a list like this.

If your device wasn?t listed then tick No, the device isn?t in the list and Windows will perform a search for non plug-and-play devices.

If Windows still doesn?t find your hardware, your last resort is to install it manually by selecting it from this list. Strangely a lot of the devices we usually install are listed under Other.
This material is the copyright material of or licensed to Future Publishing Limited, a Future Network plc group company, UK 2004. All rights reserved.


Article ID: 835829 - Last Review: 10 August 2006 - Revision: 3.3
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