Computer freezing

Hei, this could be either hardware and/or software so i posted it here

Ok, randomly when im playing CS 1.6 it freezes and what ever sound is happening at the time repeats itsself. This lasts for about 10-15 seconds and then the game returns normally about 95% of the time, and crashes my pc the other 5% of the time.

When it freezes, CPU usage is at 100% and CS 1.6 is using a crap load of mem usage.

This is really random.. sometimes it doesnt happen for a week, and other times it happens 5 times in half an hour.

My setup:

AMD64 3500+
Leadtek 128mb PCI-e WinFast PX6600GT TDH
Asus A8N-SLI SE mother board
2 x 512 pc3200 corsair value ram

I know 10+ other people who have this problem with the 6600GT and some lower grade 6000 series cards and i also have several friends with 6600's that dont have this problem.

Anyone help to fix this would really be appreciated.

Ive tried several different drivers, formatting etc and its still happening :/

please help


*UPDATE*

It just did the same thing whilst i was watching a video on youtube, except it didnt come back and i had to reset my pc. Do you think that this could be to do with the sound instead of my gfx card?