Computer freezing/sound looping

[dr.problem]

Hi everyone, ive had this issue for a while now and im still not sure what could be the problem. My computer has been constantly feezing whenever playing counterstrike or Half life 2. When it does this, the sound begins to loop, or sometimes it just makes a loud screeching noise. The computer will completely lock up, and I'm forced to just turn the power off. There is no indication while playing that the game is going to freeze (i.e. Lag). Im pushing 60-70 fps easy. I've tried reinstalling the game numerous times to see if steam was the problem, but it still does it. Ive run many spyware removers to see if that was was the problem, but each time i run it i only get about 1 bug, so that cant be the problem. Also ive checked my temp's when running the game and the processor stays at about 49 the entire time. Also, i thought that the screeching might indicate that the sound card was causing the problem, so ive reinstalled the drivers for my sound card to see if it was the problem, but the freezing still persists! PLEASE HELP!!!
My spec's are as follows;

ABIT NF7-S Mobo
Athlon XP 2800 processor
PNY 256mb 6800GT
Sound Blaster Audigy 2zs
80gig hard drive
420 Watt power supply (i think thats high enough for this hardware)
:blackeye:

 

[Anonymous Danny]

does it freeze and screech only when playing on a network or over the internet? and also, how long after u've begun playing a game or running the program that it starts doing this? it's most likely to be the hardware or the way the hardware is configured when running the game.