Many thanks for all the useful suggestions.
I pleaded severe ignorance

and the Windows Support Engineer from work has been and looked at my set-up. He banged away on the keys and came quickly to the conclusion that there is a problem with the server probably caused by the fact that I had a STB previously. This might mean that a MAC address is already allocated to me (from the STB) and why would I want another. NTL support said that they would log it as a problem to be dealt with in the next 12 hours.
I will report back - from my own PC I hope when I return from the

on Sunday.