laptop randomly locking up while playing games

I am trying to troubleshoot this problem and figure out how to stop this. Lately when i start up a game, whether it be tribes or rokkitball, the game will randomly push the cpu usage to 100% and the entire computer will stop responding for 1-2 minutes or so until the cpu usage goes down. This will usually occur around 4 or 5 minutes into a match and then randomly from then on. One thing that seems to take up a lot of cpu usage when this occurs has the image name "System" and user name "SYSTEM". When the game starts locking up it will jump from 0-1% to around 50% of the cpu usage. No idea if that could be a cause but I am running out of ideas on what it may be.

I updated my graphics drivers, my system isnt lighting fast but it should be able to handle these games, especially tribes...

I am also thinking that over time i have just filled my harddrive with too much junk and its time to reformat and get a fresh start. I am also going to defragment and things tonight to see if that has an effect.

If anyone has any ideas or anything for me to try, let me know.

when it "locks up", do you hear any clicking noises coming from the hd? and also, how big is the hd and how much space free do you have?

No the hard drive does not appear to be accessed or clicking during a lockup or nearly at any point during game play. Just some very minimal use. The bottom of the laptop gets very hot, to hot to touch almost. Could be something overheating?

No the hard drive does not appear to be accessed or clicking during a lockup or nearly at any point during game play. Just some very minimal use. The bottom of the laptop gets very hot, to hot to touch almost. Could be something overheating? ~~ not saying anything bout the hot bottom; doesn't that say anything to you?? DG~~

Specs please, all of them, thanks..

What surface are you using your laptop: table, bed, couch, ottoman????? what??

it could be throttling back the CPU to cool the thing

clear the fans and heatsinks of dust lately?

I havent and i should clean everything out but wats the best way to go about it on a laptop? one of those compressed air cans? Specs are

Dell xps M1210 laptop
windows xp
intel centrino duo @ 2.0ghz
1gb of ram
geforce go 7400 256mb

The laptop is used on a wooden desk. I am going to try setting it down on something giving some space between the bottom of the laptop and the desk as well as cleaning all the fans out. Ill also keep track of how hot the different components get and post that up after some testing.

I really think it probably just needs a good cleaning, I also took the ram out and put it back in and have noticed slight improvement, the whole system doesnt lock up but it still does slow to a stutter sometimes.

edit: just played a game, just a little stutter. The graphics card got up to 85 degrees celsius and the cores maxed at about 76.