It's not the battery because I bought a new working one for it.
Not the hard drive because I bought a new one for it and it still freezes up (which I will return tomorrow.)
Nor is it a software problem (because the new hard drive couldn't have a software problem.)
My friend told me it might be a heating problem, because my computer does get fairly warm. But it's never hot and it's always in the area where the processor is. So it doesn't seem to be any of those problems.
Any pro tips?