Sounds like a driver conflict ,but could be alot of things.
just google youre problem ,chances are someone has run into the same thing. Better to hit alot of message boards then just one
Also theres a ATI driver cleaner app that you can launch from safemode that cleans out youre previous install, before you reinstall new drivers
Might want to go with a clean install and make an image after youre done tweaking it the way you want it. That way if something like this happens again you can just reimage youre system in like 15 min. Dont use the Microsoft rollback feature , ghost an image is the way to go.