Don't know what NTL are on about!!!
The fact that
they can't get into your mate's system shouldn't come as any suprise to them, they've never been able to get into anybody's system AFAIK.
I think (and I'm sure I'll be corrected if I'm wrong

) that NTL just need to link the MAC address of the STB to your mate's account and then all should be well.
He may have to re-register the PC/STB combination.... Not completely sure what the process for that is.
Anybody else got any thoughts on this one, there must be somebody around, <shouts>HELLLLLOOOOOOOOO</shouting>
Anyway, I'm sure someone'll be along soon with a better idea (or a more technical explanation), in the mean time

to CF. Sit back, kick off your shoes, relax, and enjoy your stay