I complained enough times of Thunderbird 3.x being slow, in general not allowing me to do anything with any of my eight accounts, until e-mail is downloaded to two or three accounts. A while ago, after trying for over ten minutes, TB crashed, and when I tried to send a report, it failed to send it. After it got over it, and restarted it has worked flawlessly. This is the second time that it has a tantrum, crashed, and then did not send a report.
It looks like I am going to use Thunderbird as default, if 3.1.10 acts up again.