Computer freezes randomly when playing games

Hey guys,

I have a Dell Inspiron 546 computer. I downloaded Black Ops from Steam and it wouldn't run (Had a constant hour loading glass and wouldn't let me select any of the menu options). Anyway, I figured out I needed a new processor so I bought one from Tiger Direct. Installed it, ran game and it worked pretty good. Now the game seems to freeze up randomly!

Sometimes I'll play for a few minutes or just get it loaded and it freezes other times I'll play for over an hour and it won't freeze.

Does anyone have an idea of what this could be? Maybe my system is heating up?

BTW I can run MW2 all day long and it runs excellent.

Any help would be greatly appreciated.

Thanks, Seth.