Just been having a world of annoyance with Thunderbird seg faulting. I don't know what caused it but I did install the Netbook Unity Desktop environment (which incidentally doesn't work on my box).

So after the above I got:

This fails
myuser@mybox:~$ thunderbird
Segmentation fault

This Works
myuser@mybox:~$ sudo thunderbird

Ended up going into user & groups properties and gave my user account more permissions.

Screenshot-Change Advanced User Settings

I didn't narrow it down to the exact lack of permissions and I couldn't figure out via strace what was being denied. But this got my Thunderbird install going.