Microsoft KB Archive/95601

= Windows Err Msg: Corrupt Swap File or Unsupported DOS Version =

Article ID: 95601

Article Last Modified on 7/7/2005

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APPLIES TO


 * Microsoft MS-DOS 6.0 Standard Edition
 * Microsoft MS-DOS 6.2 Standard Edition
 * Microsoft MS-DOS 6.21 Standard Edition
 * Microsoft MS-DOS 6.22 Standard Edition
 * Microsoft Windows 3.0 Standard Edition
 * Microsoft Windows 3.0a
 * Microsoft Windows 3.1 Standard Edition
 * Microsoft Windows for Workgroups 3.1

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This article was previously published under Q95601





SUMMARY
You may receive one of the following error messages if you are running Windows and MS-DOS:

Windows 3.1:

Corrupt Swap File Warning - The permanent swap file is corrupt

Windows 3.0:

Corrupt Swap File Warning - Your swap file is corrupt

Windows 3.0:

Unsupported DOS version; upgrade to DOS version 3.1 or higher

These messages can occur after you install DoubleSpace or after you attempt to create a permanent swap file (PSF) on a compressed drive. This article covers the following subjects:


 * Attempting to Create a Permanent Swap File (PSF) on a Compressed Drive
 * Receiving the Error &quot;Corrupt Swap File Warning&quot; After Installing DoubleSpace
 * Receiving the &quot;Unsupported DOS Version&quot; Error Message
 * Why You Cannot Have a PSF on a Compressed Drive
 * Why Windows Doesn't Detect DoubleSpace
 * Troubleshooting Problems Encountered When Working Around This Problem



Attempting to Create a Permanent Swap File (PSF) on a Compressed Drive
To work around this situation, delete the PSF and create a PSF on your host drive.

The host drive is the drive that actually contains the DoubleSpace compressed volume file (CVF). To determine which drive is your host drive, type dblspace /list at the MS-DOS command prompt and then press ENTER. Any drive listed as a &quot;Local hard drive&quot; is valid for a PSF.

When you create a new PSF on the host drive, you may receive the following warning:

Windows will not use more than the virtual memory specified by the Recommended Size. Are you sure you want to create a larger swap file?

As long as the PSF is not larger than four times your physical memory, Windows can use a swap file that is larger than the Recommended Size.

Receiving the Error &quot;Corrupt Swap File Warning&quot; After Installing DoubleSpace
If you receive the &quot;Corrupt Swapfile Warning&quot; error message after installing DoubleSpace, it is likely that your SYSTEM.INI file was not changed to reflect the PSF drive letter change.

NOTE: In some cases, you do not receive this error; instead, the machine stops responding (hangs) when you start Windows.

To work around this problem, refer to the section in this article titled &quot;Attempting to Create a Permanent Swap File (PSF) on a Compressed Drive.&quot;

If you cannot run Windows because it hangs, do the following:


 * 1) Use MS-DOS Editor to edit the [386Enh] section of the SYSTEM.INI file and set Paging=NO.
 * 2) Save the SYSTEM.INI file and quit MS-DOS Editor.
 * 3) Run Windows, then and refer to the section in this article titled &quot;Attempting to Create a Permanent Swap File (PSF) on a Compressed Drive.&quot;

Receiving the &quot;Unsupported DOS Version&quot; Error Message
When you run Windows 3.0 in real mode (in order to run SWAPFILE.EXE), you receive the following message:

Unsupported DOS version; upgrade to DOS version 3.1 or higher

This message is occurs when you have a corrupted permanent swap file (PSF) or you just installed MS-DOS.

If you have SPATCH.BAT from MS-DOS 6.2 or the MS-DOS 6 Supplemental Disk, you can work around this problem by running SPATCH.BAT (regardless of which version of Windows you have). To do so, type the following at the command prompt:

spatch :

For and, specify the location of your Windows directory. For example, if your Windows directory is on drive C and is named WINDOWS, you would type the following:

spatch c:\windows

If you have SPATCH.BAT included with MS-DOS 6.0 and Windows 3.0, you must use the version of SPATCH.BAT available on the MS-DOS 6 Supplemental Disk or upgrade to MS-DOS 6.2. As an alternative, you can modify the SPATCH.BAT file provided with the MS-DOS 6 Upgrade by using an ASCII text editor, such as MS-DOS Editor, to change the SET ADDR= line in SPATCH.BAT from &quot;SET ADDR=2df2&quot; to &quot;SET ADDR=2dc0&quot; (without the quotation marks). To use the MS-DOS 6.0 version of SPATCH.BAT, use the following syntax:

spatch : swapfile.exe

For and, specify the location of your SWAPFILE.EXE file. For example, if your SWAPFILE.EXE file is on drive C in the WINDOWS\SYSTEM directory, you would type the following:

spatch c:\windows\system\swapfile.exe

NOTE: The version of SPATCH.BAT on the MS-DOS 6 Supplemental Disk and the version included with MS-DOS 6.2 work on both the Windows 3.0 and Windows 3.0a SWAPFILE.EXE files.

If you have Windows 3.0 (not 3.0a) and you run the version of SPATCH.BAT provided with MS-DOS 6 Upgrade, your SWAPFILE.EXE file will be corrupted. You can restore this file by copying the SWAPFILE.SAV file as SWAPFILE.EXE to your Windows directory. The SWAPFILE.SAV file is not always easy to find because it is placed in the directory from which you ran SPATCH.BAT. For example, if you ran SPATCH.BAT from the root directory of your C drive, use the following command to restore your PSF:

copy c:\swapfile.sav c:\windows\swapfile.exe

To obtain the MS-DOS 6 Supplemental Disk, use the order form in the back of the &quot;User's Guide.&quot;

Why You Cannot Have a PSF on a Compressed Drive
Windows accesses a PSF directly through the disk controller if the 32-Bit Disk Access (FastDisk) option is selected. If this option is not selected, Windows uses the BIOS to access the PSF. Both these methods access your hard disk at a level that is below compressed drives. This causes Windows to read invalid data and issue the &quot;Corrupt Swap File Warning&quot; message.

Why Windows Doesn't Detect DoubleSpace
Windows cannot create a PSF on a compressed volume file (CVF) created by a disk-compression program (such as DoubleSpace, Stacker, and SuperStor). Since Windows performs direct disk read/write operations to a PSF, the swap file must be located on a physical hard disk, not a CVF. NOTE: Because DoubleSpace had not been developed when Windows 3.1 was released, it was not possible to add detection code to Windows to prevent it from installing on a DoubleSpace drive.

Troubleshooting Potential Problems with the Workaround
If there is not enough disk space on an uncompressed drive for a swap file, you must either delete files from the host drive or reduce the size of the compressed drive.

For example, if your compressed drive is C and your host drive is H, you could use the following command to decrease the size of the compressed drive, creating 12 megabytes (MB) of free space on the host drive (H):

dblspace /size /reserve=12 c:

If you receive the error message &quot;Drive C is too fragmented to resize,&quot; type defrag /h /q c: at the MS-DOS command prompt and then press ENTER.

For more information on DoubleSpace, do the following:


 * Type help dblspace at the MS-DOS command prompt and then press ENTER. -or-


 * Type dblspace at the MS-DOS command prompt, press ENTER, then choose Contents from the Help menu.

Additional query words: fastdisk 6.00 swapfile dblspace double space dblspace.exe err msg errmsg

Keywords: KB95601

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