Working on a Windows 7 Home Premium 64bit machine; Using a T-Bird 32bit version. Yesterday (11/7/18) T-bird automatically updated to version 60.3.0 and then the problems started happening. Every time T-bird went to get my emails from my GMX POP account T-bird would crash. It would also leave all my emails on the server, even though the checkbox for "Leave emails on server" is unchecked, and always was. So every time T-bird would now go to get my emails, my postbox would fill with new identical versions of the same emails. I decided to deinstall 60.3.0 and revert back to 52.9.1. Now at least I can actually work with T-bird again without it causing chaos in my daily correspondence. So now with 52.9.1 I have no problems any more again. By the way, I also turned off the automatic update feature in about:config under app.update.enabled; now it is set to false. Another thing: I found another recent question in the support forum (https://support.mozilla.org/en-US/questions/1239732) where some of the answers suggested that the crash has something to do with customizing of the sound to be played upon receipt of new mail. In my case I customized the sound, so a wav file of roughly 2.5 MB plays.