This could be your problem.in device manager under display adapters, uninstall the old drivers, reboot, then install the new ones. the full suite isnt necessary, but will give you tools that could come in handy if you have multiple monitors or want to overclock the card a bit.
You should uninstall the drivers thru the Control Panel/ Add and Remove Programs option. When you uninstall the driver throught the Device Manager it unloads the driver but it doesn't remove the old files from the system.
Download DriverSweeper and install the program, but don't run it yet.
Next go to the Control Panel and uninstall the Catalyst Control Suite through the Add and Remove Programs option. Once it's uninstalled you need to restart the computer in Safe Mode (hit F8 after it posts).
Once your in Safe Mode start up DriverSweep, check the ATI Display Driver box and Leave All The Other Boxes Unchecked. Click on the Analyze button, it may take a few moments to scan the system files and registry. If any entries are displayed click the Clean button. When it's finished restart the pc normally and install the latest drivers.
You shouldn't have to go through this procedure normally but when your having driver issues it worth the extra few minutes. If the problem still persists then it's probably something else.