When moving users between storage groups Blackberry device stops working:
There are three options to fix it:
1. Restart BES services will fix the situation
2. Restart server which inturn automatically perform the step number 1.
3. After you moved the mailbox, open up a command prompt and run handheldcleanup.exe -u. You can find this tool in \Program Files\Research In Motion\BlackBerry Enterprise Server\Utility