I'm aware this has been discussed and fixes suggested, but they don't work for me so... 1. What is the difference between normal startup and troubleshoot mode? I've already turned off any extensions I can find in both Thunderbird and Firefox, but there must be something else affected. 2. What is the connection between Thunderbird and Firefox? When I choose one of the debug options in Thunderbird I get connected to debugging in Firefox, not Thunderbird (bad link?). Thank you in advance for your response to these questions. I'm hoping to be able to troubleshoot on my own since previous solutions don't appear to apply.