Valve games ****ing up my computer.

Hey all,
I would like some help.

Today I decided I fancied a Portal marathon, as I haven't played it in months and never got round to completing it etc.

But I can't get through 5 minutes without it freezing my computer, the screen going blank and the sounds looping. I have to hold the restart button for it to switch off, and it seems to be causing problems when booting also; when logging in the background shows for a while, with the icons loading eventually.

Despite it being a fresh install, I uninstalled Steam completely and tried again, installing most of the Orange Box.

And yet the problem persists, and the same thing happened when I attempted to play HL2. (I assume the rest of the games will do the same. I don't have/play many other games, but last time I tried BF2 it was fine, so (hopefully) it's just Valve games playing up.)

Any ideas what's going on/how I can fix it? I've already lost hours of fun!

Spec:
E2140 (@2.8G)
X1950Pro
4GB OCZ DDR2 1000
Windows XP

Thanks in advance.

I had the same problem with TF2 and L4D for 3 weeks. And just recently i found out it was my antivirus that was causing the problem, i had bitdefender and switched it with kaspersky.

If changing your antivirus doesnt work, reinstall windows.

Disable multicore rendering : to do this just bring up the console command and type "mat_queue_mode 0" without the "", have fun. Dante2710

Disable multicore rendering : to do this just bring up the console command and type "mat_queue_mode 0" without the "", have fun. Dante2710

Try rolling back to an older driver version.

try lowering your fsb, 2.8ghz is alot more than your processors stock 1.6ghz so it may have become unstable as time went on.ferret-gamer