wired gigabit ethernet disconnects

[mtroxel]

T42, a little over 3 years old, XP Pro. For the last few months, when I plug CAT5 into my wired ethernet port (Intel PRO/1000 MT Mobile), I get an IP address....for about 10 seconds. Then I get the red X and am told the cable is disconnected. It is not. If I right click on the connection in network connections, "Enable" is bolded....as if the NIC is disabled. When I try to enable it, an error says "Connection Failed!. If I go to device manager, there is a yellow ! by the card. If I disable it there, then enable it, I can connect again, for about 10 seconds again.

Pins in the RJ45 are all fine, I've tried several CAT5 cables. I uninstalled, reinstalled with the latest drivers. Is that part of my mo bo just fried?