Hi, Jim.
If it is not a worm, and it is not producing a BSOD, then the problem is
most likely in your hardware. Might be as simple as a loose cable, or as
complex as a bad power supply. Or bad or mis-matched RAM. Or a failing
hard drive. Or...
Do you have a trustworthy computer repair shop handy?
By the way, it will help us to follow the conversation ("thread") if you
will click the "Include original" button in your Reply. Otherwise, we have
to keep flipping back and forth between your latest message and the previous
ones.
RC