Well, that really fucked things up!
At the end of running the Spybot un-installer I got a message saying that there was a problem with BitDefender Threat Scanner, that it had created a dump file in Windows\Temp and I should inform the software developer. WTF??? I don't have Bitdefender on this PC at all. After a long search on the internet I find a post somewhere suggesting that Spybot uses Bitdefender code, so maybe that's it. The result, however, is that I get an inescapable (never goes away however many times you click) error message on shutdown, that can only be got rid of by holding down the power button.
Spybot itself may have been uninstalled, but there are shit-loads of files left on the computer, and the sdfssvc and spdupdsvc processes are still running. So, now I've got two rogue antivirus programmes messing with my system.
To add injury to insult, when I tried searching for a file on my hard drive, the search functions had disappeared altogether. No searches either from the Explorer toolbar or from the start menu, just a blank blue box where they used to be. Two hours of wasted time trawling the internet and trying different solutions and I've got a search facility back. I say 'a' not 'the' because it doesn't look the same, but from memory seems to have most of the same functionality.
For your (possible) interest, I've attached fresh copies of the FRST logs. I don't suppose they'll help, but if you think you can see an obvious new issue and no what to do about it I'd be delighted to know.
At this point, however, I have to ask - Do you actually know what you're doing trying to solve this issue, or are you just experimenting?
I don't wish to be rude, and the truth is that I really do appreciate the time you've devoted to fixing my problems (for free), but honestly it feels like I've come to you saying there's water coming in through my roof, and all you're doing is offering me a selection of different mops...
The point is, after two days of attempts to get Avast working, my PC seems to be in a worse state than when I started. It just shouldn't be this difficult.
Is there any possible reason why I shouldn't just give up and go back to AVG?
Piers.