Ok, reading through other bugs (64614) I noticed that some people have problems with assistive technologies and thunderbird.
I went to System -> Preferences -> Accessibility -> Assistive Technology Preferences and unchecked 'enable assistive technologies'.
As soon as I did that (no restart of gdm or anything) thunderbird worked again fine without me needing to run it as root.
To test I shut thunderbird, and went back to the same menu and re-enabled it, trying thunderbird again and it wouldn't start again. Going back and disabling assistive technologies and instantly it is able to start up without problems.
Hurrah! Ok, a problem for those who need the assistive technologies, but I don't even remember when I turned them on.
Ok, reading through other bugs (64614) I noticed that some people have problems with assistive technologies and thunderbird.
I went to System -> Preferences -> Accessibility -> Assistive Technology Preferences and unchecked 'enable assistive technologies'.
As soon as I did that (no restart of gdm or anything) thunderbird worked again fine without me needing to run it as root.
To test I shut thunderbird, and went back to the same menu and re-enabled it, trying thunderbird again and it wouldn't start again. Going back and disabling assistive technologies and instantly it is able to start up without problems.
Hurrah! Ok, a problem for those who need the assistive technologies, but I don't even remember when I turned them on.
Best,
-James