right my computer has started to act strange and its annoying me. the fan always comes on and can stay on for up to 10minutes at a time - it slows everything down and sometimes wont let me open up anything. now i have cleaned everything out and there was a fair bit of dust, i even unscrewed the fan and cleaned both sides. but you guessed it, the poxy thing keeps staying on then will eventually turn off.

do you know whats wrong?

 

I am not a expert on these things by any stretch of the imagination, but can't see a fan being able to slow things down.
It is more likely that you have either a baddy bug, or a fault with the chip itself bug would be my guess.
tabetha

 

did u take the actual fan off the cpu
i did this at the weekend and had to renew the thermal compound between the fan and cpu

without the compound it will run really hot as it acts as a heat transfer

HTH