NT Server- NTVDM.exe corrupted

I have had 2 server crash in the same time frame with a (Stop: bad image checksum. ntvdm.exe is possibly corrupt of missing). Now, the strange thing is I had to do a clean install of NT 4 on each machine, updated to the latest service pack,
..ect. After rebooting several times it crashed again with the same error. Does anyone have any idea why this might be happening?? Is there a virus that’s going around corrupting the ntvdm.exe file??? I’m at a lost for words especially after each reinstall still crashes.

Any ideas will be appreciated.