Hi TDiddles,
Any update for your issue?
Per your description, you have deploy a new parallel enviroment for the restore operation, that means you restore the DC and the exchange on a new server box, and the it is in a new forest, right?
Wich account do you use to do the exmerge, and what is the detailed procedures?
Did you reboot the server and make a test, if you have configure the account permission already?
Yet it is just a suggestion, not must.
Other information:
http://support.microsoft.com/kb/823143
Regards!
Gavin