Whoopee! Put working floppy in Sadj (hell the way you get into the old Dell Poweredges is really meccano!) and that made no difference but I could now run the networking wizard if I wanted to.

Ripped out the old 10base card (huge!) and popped in a little and rather more recent Sitecom and bingo!

Updated the free antivirus on that machine (Avast) - I try to run a different antivirus on each machine so that if one turns out to be vulnerable to one virus with luck some others wll get away with it.