Error Message "Invalid System Disk" After Setup Reboots

During the first reboot in Windows Setup, you may receive the following error message: You may also receive this error message when you start your computer by using a Windows Startup disk, or you may receive the following error message:

This issue can be caused by any of the following conditions:

• Your computer may be infected with a boot-sector virus such as the AntiCMOS.A virus.
• Your computer is running an anti-virus program.
• Your computer is using hard disk management software (such as Disk Manager, EZ-Drive, or DrivePro) for hard disk geometry translation. These tools provide support for large hard disks (more than 1024 cylinders) when your computer's Basic Input/Output System (BIOS) does not support large hard disks.
• Windows Setup was unable to copy the system files to the hard disk.
• Security software has disabled access to drive C.

Use one of the following methods to correct the problem.

Computer Is Infected with a Virus

Use an anti-virus program to detect and remove the virus, and then reinstall Windows. Boot-sector viruses infect computers by copying information either to the boot sector on a floppy disk or the partition table on a hard disk. During startup, the virus is loaded into memory. Once in memory, the virus typically infects any non-infected disks that your computer is connected to.

Computer Is Running Anti-Virus Software

Start your computer by using the Windows Startup disk you created during Windows Setup, and then use the sys command from the Windows Startup disk to restore the system files to the hard disk.

Some computers use built-in anti-virus software that must be disabled in the computer's BIOS. For information about how to change settings in the BIOS, view the computer's documentation or contact the manufacturer of your computer.

Computer Is Using Disk Management Software

In some cases, Windows may not properly detect that you are using disk management software and may overwrite the master boot record (MBR) information. Refer to the documentation for the disk management software you are using for information about restoring the MBR.

Also, check the Setuplog.txt file for the following statement: The preceding number (64 in this example) may vary from computer to computer. If these two numbers are different, replace the system files on your hard disk according to the instructions in the following "Reinstall the Windows System Files" section. For additional information about how to determine if your computer is using a drive overlay program, click the article number below to view the article in the Microsoft Knowledge Base:

Reinstall the Windows System Files

WARNING: If you are using Disk Manager or any other disk drive overlay program on a hard disk, make sure that the overlay driver is loaded before you use the sys command on that hard disk. If the overlay driver is not loaded and you use the sys command on the hard disk, the drive may not be recognized as being partitioned by the disk drive overlay program and you could experience loss of data or an inability to boot from the drive.

Although you can use the sys command with Ontrack Disk Manager and later versions of MicroHouse EZ-Drive (or EZ-Max) after the overlay driver is loaded, earlier versions such as EZ-Drive 2.01s require that operating system files be copied to the overlay installation disk and installed by the overlay utility. In such cases, the overlay may be damaged if you use the sys command on the hard disk.

1. Start your computer by using the Windows 95 or Windows 98 Startup disk.
2. At the command prompt, type the following commands, pressing ENTER after each command:

         c:
         cd\windows\command
         attrib c:\msdos.sys -s -h -r
         copy c:\msdos.sys c:\msdos.xxx
         a:
         sys c:
         attrib c:\msdos.sys -s -h -r
         del c:\msdos.sys
         copy c:\msdos.xxx c:\msdos.sys
         attrib c:\msdos.sys +s +h +r
   
   					

3. Remove the Windows Startup disk, and then restart the computer.

Security Software Enabled

Some third-party programs prevent (lock) access to hard disks in your computer. If this software is installed, contact the manufacturer about how to remove this software and safely restart Windows 98 Setup. For additional information about Windows Setup and troubleshooting steps, click the article number below to view the article in the Microsoft Knowledge Base:

For additional information about boot-sector viruses, click the article number below to view the article in the Microsoft Knowledge Base:

The third-party products that are discussed in this article are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, regarding the performance or reliability of these products.