BSOD while playing games

Hey all!

So recently I started having trouble with BSOD. Memtest, prime95, all go without errors. Few days ago I reinstalled windows but BSOD is still present. I downloaded and installed drivers. While having ATi 12.6 I had BSOD, so I decided to install 12.7 beta, but BSOD didn't go away. It occurs while I play games and it crashed once while I was using "Performance Information and Tools" to rate my PC. Crash dump analysis says it's driver related problem.
DEFAULT_BUCKET_ID: WIN7_DRIVER_FAULT
IMAGE_NAME: atikmdag.sys

This is from whocrashed.

On Mon 23.7.2012. 8:30:29 GMT your computer crashed
crash dump file: C:\Windows\memory.dmp
This was probably caused by the following module: atikmdag.sys (atikmdag+0x1D821)
Bugcheck code: 0xA (0xFFFFFFFFFFFFFFFF, 0x2, 0x0, 0xFFFFF80002C7CF26)
Error: IRQL_NOT_LESS_OR_EQUAL
file path: C:\Windows\system32\drivers\atikmdag.sys
product: ATI Radeon Family
company: Advanced Micro Devices, Inc.
description: ATI Radeon Kernel Mode Driver
Bug check description: This indicates that Microsoft Windows or a kernel-mode driver accessed paged memory at DISPATCH_LEVEL or above.
This appears to be a typical software driver bug and is not likely to be caused by a hardware problem.
A third party driver was identified as the probable root cause of this system error. It is suggested you look for an update for the following driver: atikmdag.sys (ATI Radeon Kernel Mode Driver, Advanced Micro Devices, Inc.).
Google query: atikmdag.sys Advanced Micro Devices, Inc. IRQL_NOT_LESS_OR_EQUAL

Windows 7 Ultimate x64
Intel i5 2500k
Asrock P67 Fatal1ty
Corsair Vengeance 1600MHZ 4x2GB
ATi Radeon HD 6850
Corsair TX 650 V2
Coolermaster HAF 922
Coolermaster Hyper 412S

I really don't have any idea how to fix it, last thing to do is install older GPU drivers. Any suggestions? :)

Bump

Everlong said:

How are your temps for your CPU and GPU etc while playing games?

What anti-virus are you running?

Temperatures are fine, not even close to limit. I've cleaned pc recently so that shouldn't be problem. And CPU and GPU are not overclocked.
I'm running ESET Smart Security.