Hi, sometime after I launch Thunderbird, I'll see the dialog captured in security-exception.png pop. If I click on "Confirm Security Exception", two things happen. First, the dialog disappears for a second and then reappears. No amount of clicking or interacting with this dialog will allow me to get past it. At this point, TB is in an infinite loop and cannot be used so I have to quit it. Second, no security exception is ever stored, permanently or otherwise. If I click on the View... button, then in the General tab I see some certification information (I don't understand this information). See certificate.png. I see Avast in there if that makes a difference. The "Add Security Exception" article shows how to add an exception with a different dialog. That also does not work. The "Confirm Security Exception" button remains disabled - please see add-exception.png. Thanks. *** This page is not letting me upload images. The upload process stalls out. I'm not sure if you are going to see my images or not.