As soon as Thunderbird opens you see the green message retrieval bar at bottom right corner of page. This bar is frozen or at least it appears not to move. If you wait about 5 minutes you see the green disappear. Then you can make 1 click of the mouse and it will freeze again for about 5 minutes. Some time in this process I get a message that a script ,that begins with the word "chrome" has stopped. This all started when Thunderbird did an update to 45.2.0. It does this in safe mode with networking also. I have installed a new router,which was painful, after this happened so I really do not want to do a restore.