I really really can't do a clean install, but I'll try the graphics driver stuff; thanks 🙂
I also did MemTest for 6 hours, no problems.
EDIT: The computer doesn't get passed the Windows loading screen now, it either freezes there or finishes loading and restarts.
EDIT: Sometimes I can get far enough to boot into safe mode, but the computer eventually freezes (mouse doesn't move, num lock stuck on, etc.)