I have been having a more widespread issue lately. Sometimes I find clients missing application from the start menu and the zen icon looks like its refreshing endlessly. If I right click on the icon and click refresh it seems to stop the endless one.
The other issue that seems to be happening even more is Users are getting an error message at login saying User Authentication Failure.

User authentication failed during a refresh.
User applications will not be available…..

This message seems to coincide with a warning message in ZCC
Unexpected exception received when refreshing handler AppModule(GeneralRefresh): Item has already been added. Key in dictionary: 'c437210fbfb637d2efc9430a0211a420' Key being added: 'c437210fbfb637d2efc9430a0211a420'

If I have the user right click on the zen icon and login, login completes just fine.
It would seem to me that these issues may be related, as I think if the machine is stuck in a refresh the user would be unable to login because it would need to do another refresh and then get stuck. Anyone have any ideas???
ZCM 11.0 windows 7 x64
Thanks, Bill