Having trouble starting a click-ones application? Try clearing the cache by using the following approach:

• Start a command window using the administrator privelege.
• Execute the following command: rundll32 dfshim CleanOnlineAppCache

This should do the trick.

If this doesn't work you can remove the local installation of the clickonce application within the following folder (Windows 7): C:\Users\{your login}\AppData\Local\Apps\2.0\

Removing all folder there will 'deinstall' all local clickonce application, please use this as your last resort!