Could you possibly explain the freezing problem a bit more?
Are you using a particular program\application when the freeze occurs?
How long from switching the PC on does it normaly run before the freeze?
When it freezes, do you mean you can not interact with the PC at all (mouse, CTL-ALT-DEL)?
Does it blue screen, or just freeze with what is showing on the screen at the time?
What makes you think messing with the CPU cooler is helping?
Can yiu reproduce the fault at any time, or is it just intermitant?
Also, have you installed any new hardware or software prior to this fault first showing?
And how long have you had the PC, What is the Operating system, when did problem start.