I've been doing some internet searching and I'll link to things that have worked for some people. stop x101 errors are tough when it isn't a voltage problem (this really does not seem to be a voltage problem), since there are so many different things that can cause it.
This can happen from bad RAM, which is why I recommended that Prime95 test. If that runs fine without any issues, then move on to the memtest86 I linked above (you download it, burn it to a cd, boot from the cd, and it runs the test). If that doesn't bring up any errors, we can basically rule out the RAM.
I have heard of other people getting this from doing a lot of virtualization as you are, here is a fix from microsoft
, although I don't think it applies to Windows 7. There may be something equivalent though.
Sort of related, people have gotten this error from problems with directx
, the latest patches fix that. Really, it can be any number of bad drivers. Since this only happens when you do a specific thing (running virtual machines), that doesn't seem very likely. (useful utility for checking drivers
if you are curious)
I have heard that it can be a problem with the BIOS itself - you could flash it - but I really don't recommend that.
All that stuff aside, if it is a hardware problem, I would expect a problem to show up with the RAM. If that turns out to be good, I think it is a Windows problem (probably not some obscure driver problem like what I just listed). I am not going to say re-install Windows, because that is a pain. But I would recommend going over to sevenforums.com
and asking there since those people know about windows things, or posting in answers.microsoft.com
if you want.
One last test that is quick and easy to run: Open command prompt as an administrator (search for it, right click and select run as administrator), and type "sfc.exe /scannow" (without the quotes).
Hope some of that stuff helps!