Hello again Howard,
The TrojanHorseDownloader Zlob DG appeared on my laptop in my AVG check tonight. I've installed the Kerio firewall and run everything else as instructed. (Except the 4 tools, each of which was blocked by KDR --could that be the Kerio firewall? I couldn't figure out how to get them to work.) I am attaching the HJT log but the AVG scan, which found over 1000 entries, was apparantly too large for the site, so I can't upload it.
I thought I was done, but alas, I guess not. Thanks so much Howard for your suggestions. I'm a bit weary but grateful.
Just a follow-up to let you know that I've deleted all the temporary internet files and cookies on the laptop, which took quite a long time. They were all on my son's screen name, and this had probably never been done before. Maybe I should run another AVG antispyware scan tomorrow in safe mode etc. ?