Question: How do installation programs determine Windows version and how can I properly reset it? Is it via a registry key or is there some file in system32 that I can add?

Background: I've been trying to install an anti-virus solution on my Windows XP SP3 machine but the installation programs keep telling me that I need a more current version of windows. Windows XP SP3 is listed among the supported platforms (AVG, Antivir, MSE). In particular, Antivir tells me that it requires Windows 2000 SP4 and update rollup, or above to work. AVG says it needs a "newer version of Windows." MSE (Microsoft Security Essentials) simply refuses to turn on real-time protection. Somehow, all of these anti-virus programs are not identifying the version of windows correctly.

Some info: All updates from Microsoft current as of June 23 2010.

I've identified my computer via: 1) My Computer -> General tab (also Start -> Run -> sysdm.cpl) 2) System Information (also Start -> Run -> winmsd.exe) 3) Command line "ver" command. All three correctly identify it as Windows XP SP3 (5.1.2600)

I had a previous anti-virus program installed and, as everyone suggests, uninstalled it prior to attempting to install the new one. I also used Revo Uninstaller to clean up unused registry keys and folders for this old anti-virus.

I've re-registered Softpub.dll, Wintrust.dll, Initpki.dll and Mssip32.dll. Still not identifying correctly.

If it was just one poorly programmed installer, I'd let this pass, but now three different anti-virus installers are all mis-identifying my Windows version.

  • I've done one complete repair using a SP2 & SP3 + updates slipstreamed disk. Same problem. I'm finishing up a second repair using the original disk and manually installing SP3 + updates; will keep this thread updated. I'm starting to think that Michael Kohne's solution to re-scan with a boot disk will be the solution. Revo's restore point was either wiped out by the repair procedure or never done (too familiar with clicking OK, OK, Next, OK.) :) – kevininspace Jun 26 '10 at 3:01
  • Problem seems to have been resolved by: -Windows Repair -Install all Service Packs and updates -Run ClamWin – kevininspace Jun 26 '10 at 16:47

It may be the case that Revo Uninstaller has broken something badly (personally, I don't trust these third party uninstallers). I'd suggest doing a repair on your installation (and reapply service packs etc) and try again.

For the record, there is an API call that can be made to identify the version of windows, however, these installers may be looking for something else which they rely on.


With the common theme being 'Anti-Virus' installers, I wouldn't rule out the possibility that the installers are being deliberately interfered with by existing malware of some sort. Use another system to create a bootable anti-virus solution and clean the machine with that, then try again.

I found this article with a list of some possibilities. You'll need a clean machine to create the USB key or CD from.

  • You seem to be missing a link. – Velociraptors Jun 25 '10 at 12:31
  • Thank you. Fixed. There are just some days that I shouldn't go near a keyboard. – Michael Kohne Jun 25 '10 at 16:30

You might want to check the registry keys under


Did you do any backups before Revo Uninstaller did its cleanup? You might be able to restore from there. If not, you should try repairing the XP installation as Rowland suggested.


Revo Uninstaller automatically (IIRC) creates a System Restore Point before performing an uninstallation (which, IMHO, all installers should do anyways). Simply fire up System Restore and restore back until the problem is fixed.

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