Valve games using up my comp's resources?

[R.U.B.I.K.]

After starting playing portal, TF2, and HL2: DM a few times, my computer starts acting up. It won't start up any more games that require fullscreen (even srb2) until I restart. The technical support doesn't seem to help much.
Is there any way to fix this so that it doesn't keep doing this again? I don't really like restarting my computer if I want to play a game.

 

[ZeldaGamer00]

Have you tried playing those valve games in windowed mode?

 

[Blitzzo]

Sounds more like an issue with your video drivers.

What is your video card? Which drivers are you on? Are you running anything that might interfere with the screen (mirror drivers, etc.)?

 

[R.U.B.I.K.]

Sounds more like an issue with your video drivers.

What is your video card? Which drivers are you on? Are you running anything that might interfere with the screen (mirror drivers, etc.)?

My video card is ATI MOBILITY RADEON X300
I'm not sure about the drivers that I'm on.
And I'm pretty sure that I'm not running anything that'll interfere with the screen.

 

[Yugi2]

I'm not really sure about this, although I had a similar problem with SADX. It kept restarting the computer after gameplay (around 20 minutes or so) and the periods of gameplay between restarts actually got shorter. If I remember right, it was because I have a generic video card. :<