Unusual Computer Freezing

Hi again everyone.

Well, the whole corrupted explorer.exe thing was resolved by returning the computer to its factory state, nothing else resolved the issue. Anyways, now, the computer is getting occasional lockups. Out of nowhere, the entire screen lags, everything freezes, but more than anything it's like a gargantuan lag spike. I am able to do things, but with an extreme time delay. It's begun recently when the cooling pad I placed underneath my computer broke, and I am wondering if its the cause of computer overheating, which mine tends to do quite a bit. The little rubber things under the computer which prevent it from sliding have actually come unglued. Yes, full blown liquidation of the glue holding them together. I downloaded SpeedFan, but are terribly unfamiliar with its use. If anyone has any solutions, or even tips, on how to prevent computer overheating, it would be greatly appreciated, thanks.