This bug was filed from the Socorro interface and is report bp-2bef44e7-8c3a-40c6-a0c7-9b8152140517. ============================================================= I found my Thunderbird had crashed with this report when I returned from lunch. So I don't know what caused this, nor did I do anything at the time it crashed.

And another fresh crash after a few weeks of silence: https://crash-stats.mozilla.com/report/index/fd26c07d-0f31-419a-8142-ab63d2140624

This is the same crash stack as in bug 960692. Updating your graphics driver might help.