Cannot search EmailXtender after upgrade to 4.81.2518

I am trying to get a client into co-existence mode...implementing a new SourceOne system with their existing EmailXtender server.  I upgraded to EX4.81.2518, and there seemed to be no errors during the upgrade.  However, when I try to launch the EX Search Plugin for Outlook it hangs, and immediately generates an error in the OTG event log:

exception in ProcessIncomingCommand SRVCMD_FETCH_SUPERVISOR_GRPS thread: 7740

I also try to do a search from http://emailxtenderserver/emailxtender, and it generates this error:

exception in ProcessIncomingCommand SRVCMD_PERFORM_QUERY  thread: 4440

Trying to search via SourceOne Search also creates the same error.

I did a repair on the system, but nothing has changed.  And after a few minutes, the exQuery services stops completely.

I've never encountered this before, and hope that someone can help steer me in the right direction to solve this problem.

Thanks.