"Invalid System Disk" Error Message After You Run Uninstal.exe

When you run Uninstal.exe in real mode, you may receive the following message:

Whether you choose Yes or No, when you restart your computer, you may receive the following error message:

This problem can occur if you run the Drive Converter (FAT32) tool to convert drive C to the FAT32 file system, and then run Uninstal.exe in real mode. Uninstal.exe replaces the current FAT32 file system-based Master Boot Record (MBR) and DOS Boot Record (DBR) with the original FAT16 file system-based MBR and DBR. Windows creates a backup copy of the FAT16 file system-based MBR and DBR in the Suhdlog.dat file during installation. When Uninstal.exe restores the FAT16 file system-based MBR and DBR, you are unable to recover any of the files located on drive C.

This problem does not normally occur because the Drive Converter (FAT32) tool removes Uninstal.exe. This problem can occur if you have manually restored the Uninstal.exe file or run the Uninstal.exe file from a Windows 98 Beta Startup disk after you convert a drive to the FAT32 file system.

Note that this problem can also occur if you install Windows, run a third- party disk partitioning tool, and then run Uninstal.exe. Programs that change the partition structure can affect multiple drives. For example, if you use the PowerQuest Partition Magic tool to change your partition structure after you install Windows, and then run Uninstal.exe, all drives that were changed by Partition Magic are affected.

After this problem occurs, you cannot recover the information on drive C. You must run Fdisk.exe to re-create drive C, and then format drive C. Then, install Windows, and reinstall programs on drive C.

Notes

• If you own a copy of the upgrade edition of Windows 98, you need to have the Windows 3.1 or Windows 95 disks available when you are prompted for an alternate location for a qualifying product.
• You must install Microsoft Windows 95 OEM Service Release 2 or Windows 98 to have access to other drives that you had converted to the FAT32 file system.

Microsoft has confirmed this to be a problem in Microsoft Windows 98.

Windows 98 Uninstall Files

In order to be able to uninstall Windows 98, you must choose to save the uninstall information during Windows 98 Setup. This information is saved in the Winundo.dat and Winundo.ini files. You cannot uninstall Windows 98 under any of the following conditions:

• You delete the Winundo.ini and the Winundo.dat files.
• You run DriveSpace to compress one of your hard disks after you install Windows 98.
• You run Drive Converter (FAT32) to convert one of your drives to the FAT32 file system after you install Windows 98.

When Windows 98 Removes Uninstal.exe

If you run DriveSpace or Drive Converter (FAT32), the following files are removed:

• Winundo.dat
• Winundo.ini
• Uninstal.exe

If you attempt to run Uninstal.exe after the Winundo.dat and Winundo.ini files are removed, you receive the following error message:

If you choose Yes when you are prompted to continue, you receive the following error message:

Uninstal.exe is then only available under any of the following conditions:

• You have a Windows 98 Beta Startup disk that contains it.
• You copy Uninstal.exe from another Windows 98-based computer.
• You extract the file from the Windows 98 cabinet (.cab) files.

For information about how to convert drives to the FAT32 file system, see the following article in the Microsoft Knowledge Base:

For information about how to uninstall Windows 98, see the following article in the Microsoft Knowledge Base:

The third-party product discussed in this article is manufactured by a vendor independent of Microsoft; we make no warranty, implied or otherwise, regarding this product's performance or reliability.