Guys, I had the same problem as you in the past 24 hours. ATI 12.4a hotfix initially did not work(grey screen and stuff). But then I've uninstaled all video card drivers and catalyst control center. EVERYTHING! Then I've just installed ATI 12.4a hotfix from here http://support.amd.com/us/kbarticles/Pages/AMDCatalyst124ahotfix.aspx and it works like a charm:)
Hope this will help! Have fun guys!
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