When I click on Thunderbird icon nothing seems to happen. I open Activity Monitor and find two instances of Thunderbird. One with a TB icon and one without. I Force Quit the one without the icon and the program pops up. This happend every time I open TB. I have tried all the suggestions like deleting the parent file the jsn file, etc., etc. I even deleted the program and reinstalled it. Nothing works. It seems to me that there should be an easy fix to this ...