Mike-Bracknell, thanks again, I think I may have a clue now. This machine is actually second hand and the owner was an avid photographer. Perhaps he had entered some Adobe details in the hosts file. I certainly haven't. So in fact those details were sort of linked to an address no longer in use?
That is possible, without wishing to cast aspersions, the way to get around registration problems with an illicit copy of photoshop is to do just that and since it then hears nothing back from Adobe it assumes all is ok.