Computer freezes during 3D gameplay

I just got a freeze within 5 seconds of loading an online match on bc2 (didnt even get into the first person yet, froze right at the kit menu). So I put the clock back to stock and it froze after about 30 seconds. I thought maybe it was a mistake... but after restarting and totally shutting off the powersupply I reloaded the game and it froze after 5 minutes. Looks to me like my computers busted! If it freezes in stock settings do you guys recommend I keep trying stress tests in stock settings? I guess I can try OCCT for an hour under CPU and an hour under GPU. (Im afraid of IntelBurnTest )

I just got RealTemp and will be using that from now on.

With regards to the HDD. I'm going to try to defragment it as I havent done so ever!

My sound is comming from a mini "Sound Max integrated soundcard" which plugs into the motherboard in a little slot. I also have an old "Yamaha" sound card that is plugged into a PCI slot that is not recognized by win7, but I use it on my winXP boot for sound recording. I'm not sure if that would affect anything?

THINGS I HAVE TRIED (that dont fix it):
- Memtest / OCCT / IntelBurnTest (30sec) All without no errors
- Defragmenting drive
- Removed the old Yamaha soundcard
- Stock clock settings for CPU and RAM
- Overclocking the CPU to many different FSB aswell as voltages
- Tried different RAM timings, freq, and voltages
- Different video card drivers right up to the newest

WHAT I HAVEN'T YET TRIED (hope to soon if possible):
- Running windows 7 off of a different SATA HDD thats not Caviar Green
- Updating my BIOS
- Reformatting
- Stress tests (full periods of time on recommended programs)
- Testing my video card on a different computer with Bad Company 2
- Disabling my sound device (SoundMax) in device manager

STILL FREEZING! I tried playing with headphones and setting both the control panel and ingame settings to headphones but it still freezes after a few hours or so.
I have played a few hours with the soundcard disabled without a freeze so far.

My friend installed Win7 with the same dvd I used and experienced these freezes right after he installed a Win7 crack (genuine/liscense crack). He claims that he hasnt had a single freeze after using only headphones while they returned soon as he used speakers. (not my case).

--> Once a freeze occurs it will continuously freeze right away (within 5-10seconds) of joining an online game. (Happens in Call of Duty 4 also). This pattern will reset once the computer is turned off totally (power supply switch).

However when I restart it, I get a windows error report claiming it was a BlueScreen and gives some info on it with .dmp file and .sysdata
Can anyone still help me out here? Or do you think this problem may just be the soundcard conflicting?

I had the same problem with my Windows 7 64 bit installation and Battlefield 2 where the game would cause the computer to freeze completely with a fast repeating buzzing sound. I had no problems at first with Windows 7 but then one day I enabled the US landscape theme and set it to automatically change the desktop background image every 5 or 10 minutes. This is when the freezing during game play started to occur. The solution, I simply changed the them back to the default windows 7 aero them with the windows logo in the middle. Ever since, no more freezing. I played BF2 for an hour straight with no problems, where as before I couldn't last for more than 10 minutes before I had to hard reboot my system. It took me a while to figure this out so I hope this helps.