When you Import a client, all you are doing is writing an entry into the cell_info file. I am sometimes able to work around this problem by editing the 'cell_info' file, making a copy of an existing line, and changing it to remove teh '-mac' entry, and adding the correct hostname
However, if this is some underlying communications problem, this method is not going to work, which you will see when you try to create a Backup specification of the new server. At this point, and case would need to be opened, and INET debugging implemented
Regarding the server that just won't install, I suspect that there is a hung installation going on, and, perhaps, rebooting the system is the only way to really clear it