Update: oddly enough, I uninstalled Lightning 0.9 via Synaptics, and then activated Lightning 1.0 via the add-ons menu item in Thunderbird. I've been using it for a day or so since, and have had no more crashes.
Update: oddly enough, I uninstalled Lightning 0.9 via Synaptics, and then activated Lightning 1.0 via the add-ons menu item in Thunderbird. I've been using it for a day or so since, and have had no more crashes.