I reinstalled the ubuntu-desktop and the stuff that it depends on.
Now, if I use the 'human' theme, then I have the same problems as before. That is, firefox always crashes on startup.
However, if I use the clearlooks theme, then firefox starts fine. Interestingly, if firefox is already running, switching to the human theme does not result in a seg-fault. This only happens under the human theme on startup.
I reinstalled the ubuntu-desktop and the stuff that it depends on.
Now, if I use the 'human' theme, then I have the same problems as before. That is, firefox always crashes on startup.
However, if I use the clearlooks theme, then firefox starts fine. Interestingly, if firefox is already running, switching to the human theme does not result in a seg-fault. This only happens under the human theme on startup.