FPS drops steadily as I play

Hi guys,

I was wondering if you guys could help me out with a problem I have. I've searched a bunch already for solutions and I've tried various things but nothing has worked.

So the problem is, when I start playing Call of Duty 4 (online) (with all the settings turned off or low, and I mean ALL of the settings), I get a great fps (70+). but about 10-15 minutes in, the screen will flicker black and my fps will drop to around 30-40, which is still definitely playable. However, as soon as it flickers the first time (happens every time), the fps will just drop drop drop until I hit single digits.

COD4 is my only new game, it doesn't happen with older games.

Here is what I've tried so far:

I've read around and heard that it could be overheating, so I use I8kfanGUI to force my fans on high before and during gameplay. CPU peaks around 90, GPU peaks around 85, Memory around 80.

I switched to the latest Omega drivers.

I thought it might have been a virtual memory thing, even though I wasn't getting any errors about it, but I increased my page size anyways

here is my setup:
dell inspiron e1505
T2500 @ 2 ghz
2 gigs ram
ATI Mobility Radeon x1400 256 mb

I know that I only meet the minimum requirements of the game. The only reason why I think my computer can run it is because my friend has the EXACT same setup (he has a nvidia quadro, i'm not sure exactly which one) on his latitude notebook with default drivers, no fan control and everything runs great.

thanks for your time

I used tweezers and dust cloths maybe a week ago to get rid of the dust around the vents. i'll go buy some compressed air tomorrow

a question on compressed air:
wouldn't blowing the vents with air blow the dust into the computer? possibly causing problems?

also, what are normal high load temperatures?

I blew out my vents with compressed air and I still get 90 cpu peak and 85 gpu peak. as soon as i stop playing, it drops 60 cpu and 70 gpu

the fan on high does not sound particularly noisy, it sounds pretty normal

it doesn't seem to be moving a lot of air though, i can't really feel a lot of air getting blown out. how strong should the output air be? i can't really feel anything

the laptop is almost two years old

the air is definitely feels cooler around the fan area, there is air flow, but i don't really know what to compare it to

forcing the fan on high, cpu stays around 43-45 degrees and GPU is a steady 60

is it possible that my fan needs to be replaced?

i think it's fixed!

I blew out the back graphics card heat sink from the outside, by sticking the little tube of the compressed air all the way in

I just played COD4 for two hours, no problems with FPS or temp:
CPU peak: 57
GPU peak: 61
Memory peak: 63

under no load, the temps are lower as well..

thanks so much guys!!

Also, just in case other people are having similar problems with FPS with their laptop:

Make sure you graphics card software's power management is set to best performance, not best battery life. A lot of laptops will switch to best battery life if you are not plugged in and this results in a big difference in your FPS