Thanks for the advice - I suspected FRST was OK, but just being paranoic (AVG hadn't reported a problem with it previously). Anyway I ran it and attach the fixlog.txt file.
I'm now running checkSUR.
And to show good faith, and because a lot of progress has already been made in a problem which has been lurking (and which I have been avoiding facing up to) for years, namely Win 7 update not working, I have donated an interim US$50 to your site via PayPal. Thanks very much! David