|I may be that some hardware issue is at fault. A restore point may help but is not a 100% fix and was a good start.|
I think I'd try the Vista DVD. Boot to it and press space bar when you see colorful screen. It should let you try to run a choice of things. You need to run microsoft memory diagnostics.
Then if it passes you may have to look at things like temperatures from fans going bad or maybe power supply going bad.
It could end up being OS still but I'd use some hardware tests. Burn an ultimate boot cd maybe to run some other tests.
"The era of big government is over," said Clinton 1996