Did you reboot the server where the BES is running ?
If you go to some pc on your network. Are you able to log as besadmin and setup an outlook profile for the besadmin mailbox ?
I never have seen this error.
I would next try to backup the database, and then, manually change to login of the besadmin to local.
see here:
http://www.blackberryforums.com/bes-...ml#post1701507
But maybe someone else has a better idea ?