I have removed the application installation from my Windows 10 PC and deleted the profile, rebooted, downloaded the most recent version of Thunderbird, and created a new default profile. Each and every time I try to compose an email message, Thunderbird crashes. Typically, I must log-off my session and invoke Thunderbird again. The MS error message is "Program is not responding". My unacceptable work-around is to draft the content using Microsoft Word then copy-paste that text into the body of a skeleton Thunderbird email form. I have been using Thunderbird for years. This problem is recent.