If all the other boxs are ok, it must be a fault with the ME box,

Youve replaced the NIC so it cant be that, does the router recognize the MAC for the Me box?

As you have said you have tried different cables etc, do you have another Me box that is on your LAN? If so compare all the network settings and make sure they are all the same

Maybe upgrade from ME if you can!

Microsoft have admitted it is the biggest abortion they have ever produced!!