Everything was enabled as indicated above. Remember, in my case the recalcitrant computer had been on the network as effectively the master computer, and it was only the move of the printer to another host computer which prompted the non-networked huff!
Anyway, I've sorted it. The way I did it was to use the XP Wireless Network Wizard on the non-communicative computer, save the settings on a flash memory stick and then transfer the settings to all the other computers via that stick. Face has been saved, the old laptop can still claim it's top dog, and they all seem happy - including the ancient Win98SE laptop which is occasionally resurrected to do some internet work.
Don't ask me how or why; it just works now!