Well, I suppose you are all dying to know what happened. First, the good bit.
All this done in safe mode with the Set Restore Point stuff disabled. Ran HJT again and got it to do its stuff on all the entries previously highlighted. Restart and ran HJT again. New HJT log (which I can reproduce here if you really want to see it) was really the old log with all the naughty bits missing. Great. Restart not in Safe Mode. Computer started and nothing was not working. Bonus.
Now the bad bits. Ran AVG anti virus. Locked up again on the 9th registry entry. Bugga! Ran Spybot. Locked up as before. Double Bugga! Ran Adaware SE. It fairly buzzed through the early part of the scan and I thought "Yes!". Wrong. It then started clocking up a huge number of objects. Left it doing so and the following day it had 92,000 thingies quarantined. Deleted the quarantined file and ran it again. Same result.
At this point my friend said words to the effect of "Sod it - I wanted a new hard drive anyway". So there I have left it. I'd still love to know WTF was going on though.