DriveSpace VxD and Real-Mode Driver Are Mismatched

If you install, remove, and then reinstall Windows 95, you may receive the following error message when you start Windows 95: When you press a key, Windows 95 starts, but it may be unstable. You may see unusual characters on the screen and you may receive "fatal exception" error messages.

DriveSpace 3 from Microsoft Plus! for Windows 95 places real-mode drivers on the hard disk that are not removed when you delete the Windows folder. When you reinstall Windows 95, Setup places a DriveSpace VxD in the Iosubsys folder that is incompatible with the DriveSpace 3 drivers.

Replace the Drvspacx.vxd file in the Iosubsys folder with the correct version from the original Microsoft Plus! disks or CD-ROM. To do so, follow these steps:

1. Restart your computer. When you see the "Starting Windows 95" message, press the F8 key, and then choose Command Prompt Only from the Startup menu.
2. Change to the Windows\System\Iosubsys folder.
3. Rename the Drvspacx.vxd file to Drvspacx.old.
4. Extract the Drvspacx.vxd file from the Microsoft Plus! CD-ROM or original disks to the Iosubsys folder. The Drvspacx.vxd file is located in the Plus_1.cab file on both the Microsoft Plus! disks and CD-ROM.
   
   Use the following command to extract the Drvspacx.vxd file
   extract <drive>:\plus_1.cab drvspacx.vxd /L <destination>
   where <destination> is the Windows\System\Iosubsys folder and <drive> is the drive containing the Microsoft Plus! disk or CD-ROM.
   
   For information about the Extract tool, type "extract" (without quotation marks) at a command prompt, or see the following article in the Microsoft Knowledge Base:
   129605  (http://support.microsoft.com/kb/129605/EN-US/ ) How to Extract Original Compressed Windows Files
5. Restart your computer normally.

If you still receive a "mismatch" error message when you restart your computer and the Drvspace.bin file is the correct Microsoft Plus! version, check for a Dblspace.bin file dated 7/11/95 or earlier. This file is a hidden file in the root folder of the boot drive. If this file exists, rename it to Dblspace.old and then restart your computer. DriveSpace 3 does not require the Dblspace.bin file to mount compressed volumes, but Windows 95 processes Dblspace.bin before Drvspace.bin if both files exist.

This behavior can also occur if you reinstall Windows 95 to a different folder than its original folder after you install Microsoft Plus!. If you reinstalled Windows 95 in a different folder and you want to use the original installation, edit the Msdos.sys file on both the host drive and the compressed drive. Make sure that the PATH statement points to the correct folder. After you edit the Msdos.sys files, save the files and then restart your computer.

NOTE: If you are using a Microsoft Plus! CD-ROM and you are not using real-mode CD-ROM drivers, this resolution does not work.

The following tables list the correct files.

Windows 95 without Microsoft Plus!: Windows 95 with Microsoft Plus!: Windows 95 OEM Service Release 2: