After installing a Nero 9 update, itunes would no longer open. After trying all of the suggestions I could find on the web (uninstallin and reinstalling, deletin bonjour, etc.), I finally got itunes to work by simply repairing the Quicktime installation. It occurred to me that the two programs are interlinked somehow as Quicktime has to be installed in order to itunes to work. I hope this helps someone else.