Hi
Windows 7 decided to get in on the act while I was eating lunch and guess what? All is working fine, the headphones now appear permanently in 'Devices and Printers' and the cats are playing with the Belkin adapter on the floor!
Thanks for you input - in following your suggestions I've learned a lot about my computer and bluetooth and then suddenly "the problem fixed itself" Windows took quite a while to locate and download drivers - but all is well! Many thanks!
Now to try to find out what is bugging my new Android tablet - which I bought for educational purposes so I can't complain if I now have to learn about how it works!
Best regards
Carl