You lucky bastard. I've never managed to fix a PC breaking issue like that by doing a simple sys restore.
It's always a broken GPU or some other shit. I actually recently replaced my old GPU because of hard freezes and crashes. Was pretty weird as it would pretty much consistently crash in some games but not in others with higher demands. Also, it often wouldn't crash while in a game but a few minutes after I closed it. So I'd be doing simple emailing or browsing and it would just do a hard freeze then. But never if I didn't play a game before. Really bizarre. Since there were so many issues but with so many different 'symptoms' (slowdowns in games, hard freezes in and out of games, BSODs, etc) I figured it must have been the GPU and replacing it did the trick. The old one was 3-4 years old anyway so eh, I guess it was par for the course.