Hi guys, I seem to be having nearly identical problems as RTW so I thought I'd share some of my experiences with it and hopefully it'll help us solve this thing together.
This happened quite a while ago and I've been trying to figure out what's been causing it. Pretty much any 3d intensive game I play (WoW, Titan Quest, World in Conflict Beta), I will get 4-5 second freezes at completely random intervals and completely random frequency. Sometimes I can play titan quest for 30 minutes and it'll freeze twice, sometimes, it will freeze once every 2 minutes or so. I have noticed however that the more stress I put on the graphics, such as running World of Conflict beta, the more frequent the freezes become (once every minute or so). I have also noticed a good amount of artifacting while playing all my games.
Here is my spec (a bit general because I'm not at my computer)
Pentium 4 3.2ghz
Asus P5LD2 motherboard
2gb Kingston DDR2 PC4200 Value Select Ram
Silverstone 500W power supply (18A each on 2 12V rails)
EVGA 7800 GT CO graphics card
Seagate 7200.10 320gb Sata HD
Seagate 7200.10 500gb Sata HD
Maxtor 7200 300gb Sata HD
At first I thought it was cpu overheating, so I bought a Zalman9500 cpu cooler and installed that. My idle cpu temps are around 40C now and 55C at load and the freezes still occur. Next, I thought it was a video card problem, so I borrowed my roomate's EVGA 8800gts 320mb graphics card to try, and the freezes still occur. Then I suspected the ram, so I ran memtest, and it found no problems, but I borrowed some ram and replaced it to be sure, and freezes still occur. I then suspected a software problem, so I reformatted my hard drive and installed a fresh copy of WinXP on a brand new hard drive. I installed the latest Nvidia drivers and direct x and the freezes still occur. This should rule out any software / driver / virus problems I'd assume.
I am now running out of ideas and parts to replace. The only things that are left that I can think of is either a defective power supply, defective motherboard, or defective cpu. Is there anyway to tell if my power supply is providing enough amps to my video card to eliminate that from the list? It seems like one of the other posters that fixed this problem had a power related problem, so I am highly suspecting that our video cards are not receiving enough power.
Also, can a defective motherboard be a possible culprit given the symptoms. Another clue is when World in Conflict beta crashes, it seems to minimize the game and my HD Realtek audio program opens up and seems to think I plugged something into the audio jacks. Maybe it's an onboard sound problem. I hope someone here can help us out, not really looking forward to trying a new motherboard. Thanks for the help.
edit: I also realized that we both have Asus motherboards, thus we should both have Realtek onboard sound. May also be a clue pointing towards the motherboard. I really hope it isn't though, since it's the worst possible thing that can break on you. Getting a new motherboard is practically like building a new computer = / .