Yesterday I had uninstalled Firefox and spent an hour cleaning the registry from Mozilla entries, cause after removing Firefox and switching to IE7 I got a lot of glitches. I googled a bit for some software cleaner which would remove these entries automatically, but found nothing. So I had to go through all the entries manually.

A rule of thumb when developing an uninstaller is: if your application registers some file associations, adds autostart entries, changes the system settings or anything else, please be so kind to restore everything back in the uninstaller. I was surprised that Mozilla developers are not aware of this rule.