Thanks for the quick reply ... I guess I should have included a bit more information as to the setup we have..
The computer we use as our "server" is not running Windows Server, rather it's just a PC running Windows 7 Professional which serves as a database network for our ERP/POS software and employee file storage.
When I exit RDC, I do not log out, rather just disconnect - so the user account on the server is still active and the program is still running while I'm not connected, however it seems that the scan manager can only keep a connection with the printer if RDC is active and sitting idle.
Weird.