I was also just about ready to break down and reformat, but I found the solution, atleast for me.
Somehow my %APPDATA% environment variable had been deleted, (I don't know how, that is something I definitely didn't do manually). I am using Vista, so I set my APPDATA environment variable to C:\Users\<Username>\AppData (I had also deleted all of my Macromedia directories and their contents below this level).