Hi Greenm,
Besides the fact, it could be indeed a NIC driver issue (check that on the deployed machine with a failed join domain action in device manager),
Are you sure that the computer gets the right DHCP entries. I mean does the NIC get the right DNS values, because if the DNS server is not the DC server, it won't be able to join the domain.
To check that out, just create a new provisioning template with just the Join Domain action (You will gain some time for your tests). But before running this provisioning template against the target machine, check the DHCP entries with ipconfig /all
Hope it will help,
Good luck!