ok. First thing to do is to go into safe mode and do a virus scan there.
to learn about safemode and how to go to it, see the following URL:http://www.microsoft.com/resources/documen...e.mspx?mfr=true
The kind of safe mode you want is safe mode, without networking OR command prompt
Ok. There, you will see a replication of your regular computer, without any of the services running. Open up virus scanners, run. Personally i suggest AVG antivirus, Spybot:search and destroy, and ad-aware. If you choose to use these, make sure to download before using safe mode.
If you have any viruses apparent, post in the virus forum, or have this topic moved.
Also, as a test, leave the computer on for a long time in safe mode (overnight, maybe, whatever period of time you would definitely get a BSOD in regular version). This is an empirical test to see if it is a hardware issue or not. If you DO get a BSOD in safe mode, it is something to be worried about. Try virus scanning, repost.