Thanks once more, P.Pand GG. I have tried everything that you have suggested but with no obvious indications of success so far. I've only been back on for about fifteen minutes and, although I've not had the dreaded magnifier thrust upon me so far, I found nothing which seemed obviously related to it in the various checks which you each suggested. I unchecked just about every box I saw which related to the display but none of them really seemed that likely.
Thank you for your suggestion about startup, Saab Dastard, but I'm not really up to messing with that yet - especially at this time of night and after a Spanish dinner to boot! What worried me is that I can see no obvious way to turn the thing off when it happens. I'd have thought that if it appeared as a result of a legitimate process then I'd be offered a simple way to get back to normal ops. Perhaps I just need to know something new to me but obvious to everyone else......Ctrl*Alt*something else, perhaps.....
You can see that I took onboard all you had to say about the WGA business but am still a bit concerned about the big brother aspect of it in the future and about other related issues. Do I expose my breast to the MS dagger and allow WGA to offer me up on a slab for all eternity, do I ignore its request to 'phone home or do I subvert the whole process as suggested and hope that it goes away?