Hi Nicholas,
again many thanks for your attempt to help.
Meanwhile I have been busy trying to fix this annoying issue, but to be honest: at the moment I'm in a complete mess.
Have restored an earlier Akeeba Backup with Joomla 3.2.2 on my site successfully.
But: guess what: the error remained untouched, still no options change possible an still no working CW multicats.
Now I'm really lost. Are there any files that remain untouched during the restore?
Currently I'm trying to update again to J3.2.3 (standard method), but this also doesn't work at all. (Update bar remains at 0%, nothing happens at all).
So the last possible option seems to take your recommendation regards your CMS update plugin
Sorry to trouble you again.
kind regards
Armin
Update, right after hitting the post-button:
have refreshed the (normal) update page of my site and now the update ran successfully.
Now for the very strange thing again: not only the options change works now, but also: CW Multicategories ist working again.
Don't have the slightest hunch what happens here (maybe 'candid camera?')
I hope we can close this case now.
Many thanks for your help again
kind regards
Armin