HD 6850 driver stops responding after installing ati driver

[shionpaula]

First of all, my computer specs:
- PSU: Cooler Master 600W SilentPRo
- MOBO: ASUS M4A87TD/USB3
- AMD PHENOM II X6
- 4GB 1333 MHZ CORSAIR
- GPU: ATI XFX HD 6850
Using WIN 7 Ultimate.

My problem: Brand new pc, formated and installed Windows 7 Ultimate with all its updates. Using the graphic drivers found by windows, gpu works just fine.
Installing 11.9 ATI driver, everytime I load a high res video, or start opening too many screens with aero the graphic driver from the video card stops working, and resets.
And until I close whatever i opened, it keeps freezing and reseting.

Really dont know what to do.
Tryed installing another video card (XFX 4650) and it went just fine. Without installing the drivers, it works just ok, no problem. Cant understand, arent drivers supposed to make your card works better? Tryed installing the driver that came with the installation disc with the graphics board, still got the problem.

Thanks for any support

 

[shionpaula]

h-e-l-p! T_T

 

[shionpaula]

a friend told me that maybe my gpu is faked, thats why when installing the original drivers it freezes
is it true?