Use the Microsoft Windows Installer CleanUp Utility to remove corrupted registry entries.
The Microsoft Windows Installer CleanUp Utility only removes registry entries created by the application installer. Files and other registry entries for the application are not removed by this utility and could cause inadvertent effects on the system if not removed.
You can follow the above steps for the Error "1635: This patch package could not be opened" -- Acrobat and Adobe Reader
I have downloaded and installed this utility. It doesn't appear on the Start/Programs list although it is on the Add/Remove programs list and appears to uninstall normally.
I couldn't get it to work. This download is from a non-Microsofy source, Seagull Scientific Inc who appear to be repuytable, but I would advise caution.
Ok, now I got it fixed. I have dual screen setup and had the second screen switched off - the Start/Programs menu was overflowing to the second screen and the program was listed at the end.
I ran it and it solved my problem. Thanks!