I've found a solution that's quite easy and fast.
No need to use driver removal software etc.
1. Just go to your Control Panel -> Devices -> Device Manager
2. Choose "View" in Device Manager and Select "Show Hidden Devices"
3. Uninstall all unused cards. (My system Win7 is running about 3-4 years now, so i've modified it a lot, had 3 gpu cards hidden).
4. Reboot, use ati uninstall utility for windows 7 , reboot and install newest drivers.