Yeah, we've seen that error message before - it's usually a red herring - it is likely a DNS or DHCP issue. I'm betting the message included the unity server name as the domain (i.e. :"The Exchange Domain Servers Group could not be found in the following domain"\\UNITY"...) - that's the giveaway that this doesn't have anything to do with the actual Exchange Domain Servers group.
This could mean you have the Unity box configured to get an IP address from a DHCP server an none was found or there's a DNS name resolution issue at play...
