Hmm so my I got my computer running for the first time in several days... Decided to delete a whole bunch of crap and defrag my hard drive. 12 hours later, I wiggled my mouse, the CPU usage shot up then the fan turned on, then it died in the middle of the defrag process. Pretty much any activity causes the cpu to overload and crash.
Maybe it needs to be reseated with new thermal paste.
Or else, format and reinstall Windows.