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Intermediate & Advanced Users

Correct some VxD faults in Windows 98, 98SE, Me

Many users report a substantial elimination of VxD-type faults by installing certain VxDs from the appropriate Win9x installation CD.

This Fix May Cure these Types of Problems:
• System instability
• BSOD's (Blue Screen Of Death)
• Mouse lockups
• Shut Down Problems
• Screen freezes (and even ALT+CTRL+DEL does not work).

Many Fatal Exceptions that can occur on a PC. This fix will cure those, and only those, related to specific VxD-related errors. You can also read Windows Protections Errors on this site.

The VXDs you usually need to install are:
configmg.vxd, ntkern.vxd, vcomm.vxd, vdd.vxd,
vdmad.vxd, vflatd.vxd, and vmouse.vxd

VMM32.VxD   [1]

98 Advanced & Intermediate users 98

Windows 98, 98SE, and ME users frequently encounter VxD-related problems and many claim to improve the situation by manually reinstalling the VxDs. This area is somewhat controversial and likely to get more so in the near future. A problem undoubtedly does exist in this area. The real question to be addressed is does the fix really work?

A device's Virtual Device Driver (VxD) is a specific Windows driver that allows Windows to perform device functions at optimal CPU speed, and permits interaction between the hardware and Windows.

The protected-mode Virtual Machine Manager (VMM, filename VMM32.VxD, located in Windows\System) is the overall VxD file that provides primary functions in Windows.

It had been claimed that Win98, 98SE and ME fail to install some of these VxDs during Windows installation, leading to a variety of problems for many users. If Windows did not, or could not, use a specific VxD then a large variety of problem would result. Note: VxDs can also conflict and lock up the system.

Your system may be made faster, and safer, by installing the specific VxDs.

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VMM32.VxD   [2]

Win9x installation of VMM32.VxD
It is accepted that VMM32.VxD is initially a basic file which is built up with additional VxDs (required specifically by that PC's own components) during Win98+ installation. Those additional VxDs are then accessed from within VMM32.VxD.

However that initial VMM32.VxD file is not an empty skeleton waiting to be filled. It is a substantial 475,084 bytes on the CDs of both Win98 ( and Win98SE ( This is the size prior to installation. It contains many components that will be used by Win9x and is added to at the time of Win98, 98SE, or ME installation.

After Win9x installation, any additionally installed VxDs will be placed in \Windows\System\VMM32. These will take priority over any previous VxD within VMM32.VxD. The size of VMM32.VxD in the Windows\System directory after installation will vary from system to system. It will now be substantially (perhaps twice) larger than the CD version and should carry the date of your last installation of Win9x. The increased size is partly the result of specific VxDs being added during Win9x installation.

To view the contents of the 'new' VMM32.VxD run RegEdit and go to the Key:
where the right pane shows all the files that comprise VMM32.VxD.

It is now said that ALL the VxDs required for your own system will be present, though you could check your own Registry just to make sure.

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VMM32.VxD   [3]

Myth or Fact - are some VxDs not working correctly?

It was always likely a claim that Win9x failed to install appropriate VxDs would be controversial. The fix was to manually install some specific 'missing' VxD files from the Windows CD with the purpose of eliminating many of the Win98, Win98SE, or Win ME, errors encountered by many users (VMM errors, erratic mouse, blue screens, error messages, shutdown problems, and the like).

THPC has been uncomfortable about 'missing' VxDs, is not the original source of the fix and has declared so on this Page from the very start. The fault-fix was taken as forwarded to THPC and relayed to its visitors. Further research appears to justify THPC's unease. From looking in the Registry it appears those VxDs are installed when Win98+ is installed and are not 'missing'!

Yet major questions remain. Are they installed correctly just because the Registry identifies them as part of VMM32.VxD? Are they functioning correctly from within that file? Are they especially prone to corruption within VMM32.VxD.

Many users claim, and continue to claim, that their systems improved when the appropriate VxDs were added manually to Win98, Win98SE or Win ME.

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Just what should Win98, Win98SE and ME users do?

It is undoubtedly true that many users' systems have benefited from the installation of some specific VxDs (or all seven of them). It is unlikely your system will show any signs of improvement if you are not having VxDs-related symptoms.

It is likely that users are encountering these errors because of
1. corruption of VMM32.VxD (or some of its VxD components), or
2. they installed device(s) since installing Win98, 98SE or ME (hence the required VxD is 'missing' from VMM32.VxD and not found elsewhere by Windows),
3. they possibly have device conflicts and Windows is not coping.

The users most likely to gain from manual installation of VxDs are:
1. those who 'upgraded' from a previous Win version i.e. did not use the full version.
2. those who added new device(s) after the last full installation.
3. those who are getting repeated VxD errors.
4. those who have repeated VxD-related 'symptoms'.
and, possibly, some of
5. those who repeatedly encounter non-specific errors.

For many users it will be a matter of 'try it and see'.

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What Search Engines show
THPC looked at Keywords used in Search Engines that hit this Site. The following relates ONLY to those users who search for something about VMM32.VxD i.e. for VMM32.VxD (VMM, VMM32, VxD) itself, or specifically for one of the seven VxDs, like ntkern.vxd.

For every 100 hits, only 40 (40%) are general (like VMM, VMM32, VMM32.VxD, VxD).
The other 60 (60%) are for specifically named VxD, especially ntkern.vxd (28).

60% is significant as it strongly indicates most users are not merely investigating the 'hype' about VMM problems - such searches would not be so specific. It's likely they know they have a problem with a specifically named VxD (Windows told them?).

The total number of specific VxD searches to ONLY THPC from just ONE Search Engine is very high. Only a miniscule percentage of those searching the Web for specific VxD fixes / information will have used that single Search Engine and only some of those will have arrived at THPC. A very large number of Win9x users must be searching the Web for specific VxD file information EVERY DAY.

You are not alone. There has to be a massive VxD-related, or conflict, problem out there! Very many Win98 98SE and ME users share your problems. Reasonable conclusion?

But is most of it really a VxD-related problem that can be alleviated by manually installing VxDs? Or it it mostly some other problem, such as device conflicts? Tell THPC your own experience and perhaps we will find the answer (see Survey, this Page).

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Lets find out if the VMM32.VxD fix really works

The only sure way of judging the reliability of this 'fix' is for each of you to E-Mail THPC at reporting on your own experience after installing the VxDs.
Plenty of users are manually installing some, or all, of these VxDs.
If you do so then PLEASE lets us know how you get on.
All replies will be treated with total confidence. Note: THPC is a personal Site.
Only the overall success (or failure!) rate will be posted on this Page.

1. Bookmark this Page now so you can return here after installing the VxD(s).

2. E-Mail THPC at some time after installing the VxD(s)
3. Enter VXD REPORT as the Subject
4. Select ONE of these - the nearest to your own experience after adding the VxD(s)
        VXD result with Win? = Much Better
        VXD result with Win? = Better
        VXD result with Win? = No change
        VXD result with Win? = Worse
        VXD result with Win? = Much Worse
     and enter it in the BODY of the E-Mail, replacing the ? with your 98 or 98SE or ME.


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VMM32.VxD FIX  [1]

If you are currently having problems

Well. For the moment it remains 'unproven' that installing the appropriate VxDs actually does alleviate some problem(s). However there are strong indications from all over the Web that many users have benefited from doing so. And there should NOT be any ill effects from using the fix.

If you do not have VMM-type problems then just backup Windows\System\Vmm32.vxd NOW!

So what can we do when we do have problems?
1. You could install (from DOS) your VMM32.VxD backup - but do you have one?
2. You could do nothing and just put up with the errors!
3. You could try rebuilding VMM32.VxD - difficult procedure not recommended by THPC.
4. You could re-install Win9x - and, of necessity, re-install everything else (32-bit)!
5. You could install the appropriate VxDs (as described here) to see if your system benefits - if not, you lose nothing, except a few minutes work.

If you do the installation(s) PLEASE E-Mail THPC at with the result. See Survey (above).

As always, THPC presents you with the information available, the possible cure(s), and then lets YOU decide. Be wary of Sites that have a dogmatic or absolute approach.

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VMM32.VxD FIX  [2)

Identifying your current drivers:

1. Go to
Start • Settings • Control Panel • System
• Device Manager • System devices

2. Highlight System board
and click Properties, Driver tab, Driver File Details

3 You will see C:\Windows\System\vmm32.vxd (configmg.vxd)
then you will know that configmg.vxd is the VxD to use with that device.

4. Do likewise to check the other VxDs

After your own installation of configmg.vxd,
you will see that C:\Windows\System\vmm32.vxd (configmg.vxd)
has changed to C:\Windows\System\configmg.vxd indicating that Windows is now using your installed version of that VxD.

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VMM32.VxD FIX  [3]

Those VxDs:

The seven systems VxD drivers under discussion are:

configmg.vxd configuration manager for the motherboard

ntkern.vxd kernel driver used for the universal host controller

vcomm.vxd communications driver

vdd.vxd video drive device

vdmad.vxd DMA controller driver

vflatd.vxd video flat-frame buffer virtual device

vmouse.vxd mouse driver

You may not need all of them.
Install all seven only if in doubt.

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The specific VxDs are in the *.CAB files on the Windows installation CD, or on the hard disk for Win Me. Some are specific to their own version of Win9x.

WIN98: Look in and
WIN98 SE: Look in Win98_53 and Win98_54, or Win98_50 and Win98_51
WIN ME: Look in and

1. Pop in your installation CD (and Exit the Setup, if necessary)
2. Open Windows Explorer and highlight the CD drive (left pane).
3. Next right-click (right pane) the correct *.cab and select View
4. Now highlight and right-click the *.vxd file you want. Select Extract
    Extract to Windows\System\VMM32 and Windows\System
5. Close Windows normally, and Reboot
6. Check that the new VxDs are being used (the brackets have gone in Device Manager)

Use the correct versions of these files.

You must be ABSOLUTELY SURE the file(s) you use are an EXACT match for the VERSION of Windows installed on your computer. Failure to do so will likely damage your system, and you may have to reinstall Windows.

If the fix does not appear to work, it should not have any affect at all. You can then, optionally, leave the file(s) in C:\Windows\System and ...\System\VMM32 or delete those file(s).

(Thanks to Tom G who originally alerted THPC to this very real VxD problem).

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The fix will not work in every situation but trying it will NOT cause any harm. Also, occasionally it works only for a while. There's still a further variety of possible VxD fixes available to you.

The page at the following link describes what else you may do to eliminate these 'beastly' errors:


Read the page fully and then select the item(s) that most accurately reflects your current situation.

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Please remember that you alone are responsible for the consequences of any changes you make to your computer hardware or software.

Copyright © LarryM 1998-2015