1.] Completely un-install ATi driver, reboot and use "Driver Cleaner" to remove all traces of the driver.http://phyxion.net/Driver-Sweeper/Driver-Sweeper/
2.] Re-install ATi Driver by downloading the latest version from AMD website.http://www.amd.com/sg/Pages/AMDHomePage.aspx
P.S. if the problem still continue, please check your memory slots. Please burn this as Live DVD / CD to test your memory.http://www.memtest.org/#downiso
Optional (SSD User Only!) ------------
If you use SSD drive, please Disable ‘Superfetch’. That can kill / hang your system or even cause BSOD.
Disable ‘Superfetch’ (Windows 7 / Vista)
Superfetch does look great and helpful if you are NOT a heavy user like me. But, it sure does KNOW HOW to strangle system memory!
1.] Click Start >> Right Click: My Computer >> Manage >> Services and Applications >> Services
2.] Locate this process and “Disable” it – celetape it against the wall if you want…
Services (process): Superfetch