Hi, Thunderbird has stopped working. Nothing has changed on my computer. I'm running OS X 10.6.8 (yes I know it's old but it's been very stable so why change...), Thunderbird 45.1.1 and I installed Avast Security software for Mac 2015 a few months ago. When I open and it starts trying to pull down my messages it stops and says 'SECURE CONNECTION FAILED' and goes on to say in error message that www.mozilla.org isn't a trusted website. I'm a googlemail user. So Thunderbird is retrieving messages from an IMAP gmail account. Once this happened on Thunderbird, it has also impeded my ability to get to my gmail through my browser. Both problems started at the same time. Anybody? I have a sneaky suspicion it has something to do with Avast but would love to know. Also the TB error message flag that comes up in the corner says Advanced IMAP server settings, change number of cached connections... I've lowered it to 1 per other troubleshooting threads. Doesn't make a difference. Problem not solved. thanks!