Thanks for your reply - I did suss that and it worked briefly. However, unfortunately I now have the the problem of getting NTL to recognise my powerbook as a legitimate computer on my account. I set up as the initial account on another computer (my wife's iBook running os 9.1) and then found a handy hints and tips guide at http://homepage.ntlworld.com/robin.d.h.walker/cmtips/
but it would seem that I have to unplug the stb to reset it each time I switch between computers... grrrr. NTL tech support did respond with the same instruction you gave and said that at present they are providing "courtesy support" only for OS X. Oh well, give it another try..