BLANK Cloud Screen http://forums.adobe.com/message/5484303 may help
-and step by step http://forums.adobe.com/thread/1440508?tstart=0
-and http://helpx.adobe.com/creative-cloud/kb/blank-white-screen-ccp.html
or
A chat session where an agent may remotely look inside your computer may help
Creative Cloud chat support (all Creative Cloud customer service issues)