A short time ago I had a problem with the Adobe CS3 and CS4 applications, Illustrator, Premiere Pro, Dreamweaver, and others quit working and gave an error message similar to "Licensing for this product has stopped working".
In searching for a solution I came across this little tool that solved my problem, it is supposed to work for:
Acrobat 8 and 9
Creative Suite 3 and 4
Photoshop Elements and Premiere Elements
Director
Technical Communication Suite
If you are having problems and getting licensing errors with any of these products this tool is definitely worth a try
http://www.adobe.com/support/contact/licensing.html