Hi..I am having exactly the same problem. I have tried everything that you have suggested. In the latest Command Prompt suggestion..all goes well until the two ren statements..these do not execute, I get an "Access Denied" error for both..I am running the Command Prompt as Administrator..
Later: I just re-ran the Command Prompt suggestion again:
1: net Stop msiserver gave a message "The Windows Installer Service is not started
2: ren C:\Windows\System32\catroot2 catroot2.oldnow says that it can't locate this file.