Many thanks for all your thoughts and suggestions - they were all good.

However, I now know the answer to the problem was hidden in the question.
I've run AdAware and Spybot
It was TeaTimer running under Spybot. It was going mad and hogging all the Admin Resources. So, beware if you use TeaTimer. Some folk say it works ok on their machine, yet others complain how Bad it is.
Anyway, it's mended now, and admin is happy again, so thank you for trying to help me.