I bought my elderly mother a new macbook pro 13 to replace her dying ibook G4. Apparently (I'm helping her from 3000 miles away), her old ibook was plugged directly into the ethernet out on her cable tv box. And this worked fine. Network was setup for DHCP. It would get an address and there would be internet access. But if she plugs her new MBP into the same ethernet port, she gets no DHCP assigned address (just a random one that happens when there is no DHCP), no router, no DNS. The status of the ethernet in the networking preferences is green though, it says connected. But DHCP does not seem to work. I had her compare the settings side-by-side between the two computers, and they are the same. Anyone have any ideas on this? Are cable boxes someone programmed to only recognize a certain MAC address? Seems unlikely.