my friend contacted my earlier today about his PC shutting down:
PC just arbitrarily shuts itself off (not touching anything)? It just decides to do a hard shut down periodically. Started doing this several times per day now. Hardware or software issue? I ran a registry checker on it and found a bunch of problems and cleared them off but it’s still doing it (just did it again minute ago).
I suggested it may be related to overheating, especially the CPU fan and he informed me that it's a laptop (no cpu fan(?), but he'll check the case fan when he gets home.

Any other ideas?