Running Windows 7 Pro on a Lenovo W520. Here are the first crash reports from today: bp-49a22e1e-46bf-4c55-8283-3bbfa0180529 5/29/2018 bp-b9bbe259-58f6-43e7-89cf-6acc20180529 5/29/2018 bp-d3d80812-70c9-4795-90c4-7b6ed0180529 5/29/2018 bp-94a0431c-dac6-41a2-90e7-391fe0180529 5/29/2018 bp-5c6d41da-3799-4879-a252-a128f0180529 5/29/2018 After restarting with only Calendar (Lightning 5.4.8) and ActiveClient Security Module (7.1.0.139) enabled, it still crashes, although the display fault message did not appear. FWIW, TB has become very slow to startup, but I've attributed that to the size of my profile folders, which have become quite large over the years. These crash reports were submitted with both Calendar and ActiveClient enabled: bp-f78562f5-a9fa-45b0-98aa-a91ea0180529 5/29/18 11:11 AM bp-2c933bc3-82ed-4274-9f90-556d00180529 5/29/18 11:07 AM bp-31bf1b4b-960a-4e8a-a7d8-9d87f0180529 5/29/18 11:05 AM I restarted with Calendar disabled, ActiveClient enabled, and was able to send email without issue. However, after trying to compose a second email I experienced display blackouts and the TB display required clicking on it prior to reappearing. Then it crashed again (11:22). I disabled ActiveClient and enabled Calendar. When composing an email it crashed again (11:25). So, apparently the only way to run TB is in safe mode. bp-f04797b1-74dd-472d-96aa-d45520180529 5/29/18 11:25 AM bp-cf04240c-9309-4f29-8a06-992d00180529 5/29/18 11:22 AM After this last crash, I tried to post this report using FireFox ( v60.0.1 32 bit), but FF was no longer connecting on any tab, just bouncing dots on the tab headers. I started up Internet Explorer and pasted in the support page from FF and submitted that way, it had no problem connecting. Coincidence?