If you can't expand folders on network drives then the user you are currently DS authenticated as probably doesn't have sufficient rights.
You may need to double check the logged-in user ("sort-of" shows in the bottom RH corner of AS7 window). Poor design.
Or right-click on the target object and select "Security..." and check the current user (cancel this screen, don't go ahead and log in again!).
Even if rights have been assigned, with some DS problems I have seen the rights "vanish" and have to be resassigned. As a minimum the user needs supervisory object and property rights to
AQ6_*, AS_BACKUP_SERVER, <servername>, <servername>_VOLUME, <the user itself>
Mark