'msi not found' update problem
I use Windows 7. There's a simple solution if Windows is your Operating System. Go read my post regarding your problem. Just type MSI in the search box and (in the search results) look for the yellow triangle with the exclamation point next to the listing. You'll find simple, step-by-step instructions.
For other install/uninstall solutions, I use 'Revo Pro Uninstaller'. It tracks installations, and can uninstall EVERYTHING, including leftover Registry entries, subdirectories, etc., for a total wipe of pretty much any program.
First, READ THE INSTRUCTIONS for Revo and any other utility program you use.
WARNING: ALWAYS BACK UP YOUR CALIBRE LIBRARYBEFORE YOU UNINSTALL, just...in...case!! This goes double for the less-experienced user.