My Intel Pro/1000 MT Dual Port Server adapter was recognized by Windows when I installed Server 2008 core, but only one port works. When I connect with device manager I can see 2 Intel Pro/1000 MT adapters listed and they both have the same driver, version 126.96.36.199. I tried switching the network cables and the same port still works, so I know its not a cable / switch problem. The first thing I noticed is both adapters have the same Physical Address: FF-FF-FF-FF-FF-FF. I then assigned both NIC's a unique Physical Address via adding a registry key called "NetworkAddress". After rebooting both NICs display the new address when I do an ipconfig/all but still only one port works. I also found the port that doesn't work never detects when the cable is disconnected like the working port does, it always just sits there with an IP of 169.254.x.x.