Could have been a bad install, I think I might have had that happen to me once... can't remember but I've had some issues after a new driver install. Nothing a fresh install won't fix.
You're going to need Driver Sweeper. Just download the latest drivers, 10.12. Open your Add/Remove Programs and delete all your ATI related stuff. Then run Driver Sweeper and completely remove everything ATI (also if there's any Intel or Nvidia drivers, delete those too!). Reboot the system (resolution should be crap). Install the ATI drivers, reboot again, and it should all be working fine. Check it out.