Uninstall your current ATI driver and restart and boot to safe mode
go to my computer - click "uninstall or change a program"
find amd or ati graphics drivers/ catalyst control panel and click uninstall
safe mode - press f8 after restarting after post but before windows logo
or - type msconfig into start menu search and hit enter - select boot tab - select safeboot (remember to undo this after all is finished)
In safe mode run driver sweeper - click on ATI - click on Clean and restart (make sure to reverse safeboot in msconfig) and boot normally to windows