Try this simple test. Remove the case cover. Better, same?
After hours of leaving my computer on and running my cp (dell d600XP sp2) it crashes, a blue screen will appear and it basically says that windows has shutdown to prevent further damage, a fatal operation that is crucial to windows has unexpectadly shutdown, been deleted or is missing. if this is the first time you've seen........ i run several anti virus, rootkit anti spyware programs and all detect nothing other than tracking cookies. This has happened several times to me. Any help is greatly appreciated.