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