My Macbook Pro has been crashing - sometimes Firefox, sometimes Thunderbird -sometimes multiple times/day. I've saved many of the crash reports in case they might help someone know how to fix this. An Apple tech person diagnosed my memory was broken, so I just got a new logic board and reinstalled all my data from my Time Machine backup. Then a message popped up that Thunderbird was damaged and should be put in the trash. Around the same time i replied to an email from someone at Thunderbird donor who was responding to a question i had about a small donation i tried to make - i explained i was having trouble with Thunderbird. At that time, i could see the Thunderbird icon in my task bar. When talking with someone from Apple support this evening who was helping me answer a couple of questions, including about a new "mail" icon that showed up in my task bar, I mentioned that i'd like to learn how to back up or archive my emails in Thunderbird. That's when i saw that the Thunderbird icon - had disappeared. The Apple support person and i searched all over my computer for the Thunderbird app, but couldn't find it. I'm really nervous. I have over 300,000 emails I've been wanting to learn how to archive - or something. I don't want to delete most of them. I hope someone can help me find everything. Thank you.