Thanks for your quick response, Parapunter. Just to clarify, I'm not trying to scan for channels over the network - my daughter's PC is connected directly to the same aerial (and via the same socket) as my own PC in the room immediately below (and the cable lengths are probably about the same).
I am, however, relying on the network for Media Center to get its internet connection, through which (I assume) the TV settings and EPG are supposed to download. My issue seems to be that, although the PC can connect to the network and thereby to the Internet, Media Center itself can't.
I'll certainly have a look at the Green Button site - thanks for the tip.
Gadget 