There are a couple of programs which may, (and I do stress MAY), help you track down the culprit.
Blue screen of death (STOP error) information in dump files.
Resplendence Software - WhoCrashed, automatic crash dump analyzer
However, when I had this problem earlier in the year, I found it impossible to track down. I strongly suspected the Motherboard and so replaced it with a cheap one and was away laughing again. A tiny component which goes faulty can drive you bonkers, LOL. Am now looking at a more expensive replacement seeing that the RAM, Graphics etc have been cleared of causing the problem.
Cheers