HL2/HLDM/CS:S game LockUp

[DrawingFlies]

:sniper:
When I am in a steam game, sometimes I get a freeze of the screen, and the audio just repeats as a 1 second clip, over and over. I have completed many RAM errors checks, and it doesn't fail...(memtest for 4 hrs)
With 1GB mem, I wouldn't think I am running out of mem, have there been any other instances of this? Is it a steam issue?
I am not OC'ing anything but 6600, and it is stable at a mild OC of 530/1050.
Please give me insight to this problem I have.
To exit, I must manually turn off power to sytem, alt/ctrl/del won't work.
It just keeps repeating until I turn it off.
HELP! - - - - - - - - - - - - - - - - - - - - - - :cheers:

 

[Dinkleberry]

Diagnosis - you've got the Source plague. Try disabling AGP Fast Write in bios as a first resort then post again to tell us the result.

 

[DrawingFlies]

I am guessing you are referring to the AGP multiplier? Mine is set to Auto Detect.
Choices: 8x,4x,Auto / My card is an 8x.
Please clarify if you have time.
I first went to Steam Help, and verified files. All OK. No downloading new files when restarted.
No Good.
I next unistalled HL2, and all related files, searched for any remaining files, deleted those, went into registry, and deleted all remaining entries pertaining to HL,source,valve. Then ran CCleaner to find anything I missed. Fresh start.
No Good.

:sniper:

 

[Jangle]

i think i have the source plague as well. ;( and valve help and support sucks

 

[DrawingFlies]

This is the error I recieve when The Game Crashes into endless loop with froze screen:
One of the few times I was able to stop it with "Task Manager"
http://i3.photobucket.com/albums/y99/drwngflies/HL2Error.jpg