Unable to join the domain with Windows 7 professional
Check the Device Manager and make sure the network card is ok.
Also check to make sure the correct protocols are installed. Right Click the NIC and choose properties. "Client for Microsoft Network" etc should all be there.
You also want to check your Services. Computer Browser, WorkStation, Netlogon, etc should be running.
It would appear that there was something wrong with the image used to ghost the machine from. A re-install from scratch using the DVD resolved the problem.