If you are running Window 8 and have an AMD/ATI graphics card or embedded graphics, do not run AMD_Cleanup_Util_1.2.1.0.exe. This is a utility that you can download from AMD.com. It's suppose to cleanup files leftover after uninstalling the Catalyst. This will destroy your system. I had a horrible weekend trying to discover what caused the corruption. I didn't know anything was wrong until I tried to go into the User Accounts and into the Local Security Settings. I couldn't get into my account, couldn't do a system restore, couldn't boot into safe mode, couldn't uninstall programs, etc.. I was forced to do a Refresh PC, which retains you data but requires you to install all your apps again.
I see after doing an internet search that others have run into the same problem.