It isn't uncommon for something to go wrong when installing, uninstalling,
or updating a program on a Windows system, and this happens often enough that
Microsoft provides a special troubleshooter "Fixit" for fixing this sort of
problem automatically. Step-by-step instructions are also given if you prefer
to fix it manually.
http://www.techsupportalert.com/content/how-fix-problems-when-windows-installer-or-uninstaller-doesn-t-work.htm
