I am a person who's alway trying new programs... and other stuff. If I don't run a cleaner for a while... when I do-- the debris from old uninstalls would fill a book.
Some of those bits of code can interfere with other apps when they try to run. Especially security -- firewalls/AV... it can also interfere with new installs.
Im in the same boat as ih8bills too.
Thanks uncleed and ih8bills!