Counter-strike bottlenecking?

I'm running an Athlon64 6400+ w/ 4gigs of ddr2 pc5300 (i think?), an Nvidia GeForce 8800 GT and Vista 32bit. My computer's performance in 3dmark and other games seems to be solid and consistent. Lately, when playing Counter Strike source, every now and then my computer will completely lock up (sound repeats which is annoying) and everything seems to struggle and halt. After 30 seconds or so it will go away and then it will happen again a few minutes later. I have my core temp at 52 degrees which I know is a little warm and my fan speed is upped to 80%. Other than possible heat, does anyone have any ideas on why a good performance machine would struggle and bottleneck like this? Sometimes Vista will tell me that the display driver stops responding and then vista mentions that it recovered and everything is fine. Sometimes I get a blue screen of death and the comp reboots. Outside of temperatures I cannot really think of anything else. Any suggestions?

I've already updated to those. I just busted a Windows Update as well. I'll see if there is any difference.