Thanks very much for this, Davey. I ran DAF, following the instructions to the letter without understanding what it was doing, and only one Registry entry now recurs (touch wood !).
The only one left now is
Problem: invalid default icon
Data: C:\Program files\ZoneLabs\ZoneAlarm\UpdClient.exe,-279
Registry key: HKCR\ZAMailSafe\DefaultIcon
I haven't a clue what this means. I don't know whether to just leave it or persist in finding the cause and a solution.
By the way, about donating to free software sources, I would like to do that but I refuse to click on PayPal buttons for fear that they will lead me to a bogus site that keylogs my password (as happened to an acquaintance last year, but fortunately he noticed what was going on and backed out before any damage was done). I much prefer to log in to Paypal myself and simply enter the email address of the intended recipient. I wish the creators of freeware would let me do that.
Paddy