I don't think that's it; I hadn't touched the sources, except to add
another repository (so I could install OpenOffice.org
3). The problem
was present right from when I first installed, it seems. I'm sort of
thinking that I should just do a clean install. That seems to fix
everything. I also have a proper 8.10 release this time too.
It could be something to do with setting the software
correctly before starting these managers up.
I think there should be something called "Sources" or similar on the
system menu. It may need these set right before first starting.
Maybe just starting is sufficient to get some basic settings and
repositories but needs to be restarted before they become effective.
Just a theory.