Sudden PC restarts while playing Company of Heroes or Call of Duty 5

Hi everyone!

Im not a Newbie to PC and Games and experienced with drivers etc... but Im completly frustrated about this problem:

I have a problem with any NVIDIA Geforce driver above 178.13 and playing Company of Heroes or Opposing Fronts... this is the last working driver for my MSI Geforce 8800 GTS 512MB Card. With any other driver above (also with newest 182.50 and all between), company of heroes (and OF) are crashing with a complete pc restart when there is action on the screen after 10-20min...

My temps of the graphic card and quad core cpu are completely normal, i already tried increasing my fan to reduce them further , same problem with 10 degrees less! My PSU ist a 600W Toughpower ATX, so no problem with the power support.
With the 178.13 Driver i can play for hours and hours without any problems...

I tried all possible solutions... upgrading bios, slower tact rates of my graficcard and processor, deinstalling all previous drivers and the drvier sweeper to wipe everything out,... nothing works. I always installed with antivirus off and "clean" (after deinstalling older driver)

I dont think its the temperature of anything because my graficcard has the same temperature with 178.13 or 182.50 (and the processor too)! But with anything above til 182.50 it crashes (without bluescreen, its a sudden shutdown and following restart, no error message), with 178.13 its fine... no temperature association!

I also tried all combinations of installing and deactivating physX ... installing 8.9.x and the new 182.50 driver, installing the new one (9.03.x) with the new 182.50, also new physX and the working driver 178.13... and disableling physX totally before gaming ... i dont think its a physX problem! Installing the new 9.3.x physX and 178.13. Driver just works fine, so its a problem with the newer geforce driver above 178.13!

Anybody has any clues how to get rid of that anoying problem?
Its difficult because i dont get any error protocol when restarting, even after activating it in the system settings...

P.S: Found out its also happening while playing Call of Duty 5

Much Regards!

try to run memtest to see if your memory is good.

Post your system specs.
Maybe a new driver for it could help.

I meant the MB drivers

Man if you didn't explain it the way you did I would definetly be pointing at that PSU unit... +1 for gamerk316... If it isn't broke don't fix it. Definetly a strange issue for sure. Let us know if you get her fixed up!

whats his mobo? That would be the next logical step...