OK, I don't get this at all. I have a very nice Dell XPS M1210 laptop with quite a lot of memory and RAM. However, lately (usually while playing a game such as Portal, though it's sometimes happened just while doing something like chatting on MSN), the game will suddenly freeze, my computer will heat up like crazy, and if I manage to get into the Task Manager before everything completely freezes, the CPU Usage is at 100%. It just confuses me so much because I would be able to play it perfectly for 5-10 minutes before it freezes like that.

I've already tried scanning for viruses tons of times (I didn't find any) and I've run countless Ad-Aware scans. I've also done a disc cleanup and a disc defragment but it hasn't changed anything.

Here are my computer specs:

Microsoft Windows XP Media Center Edition
Dell XPS M1210
Intel(R) Core(TM)2 CPU
T7400 @ 2.16GHz
2.16 GHz, 2.00 GB of RAM

I really hope that someone can help me because I am very confused.

It sounds like your video card may be overheating. If you've got a program to monitor your video card temperatures (i8fangui, maybe?) then look at that periodically when running games. If it goes over 100, then that's your problem

. i would review ur current active processes and see if u can remove some or all the ones that u dont need to always be on.
. any schedule tasks and services out of the norm?
. making sure that ur working area getting enough airflow can also help.

cheers ...