Yesterday I opened computer log in Thunderbird to check mail. Everything seems to be OK. I was able to do something (access menus, deleting, etc.) in the first 5 seconds (+/-) but after this got a "not responding" message and everything freezes. The only solution is to close. I was able to repeat this opening and closing so I tried the update. After 4 open/close operations I successfully update to 45.1.1. version but the problem remains. I will appreciate your help to solve this problem System informations: - OS Windows 10 Pro version 1511 - Bitdefender Total Security 2016 - Thunderbird 45.1.1. Other information: I use Thunderbird for some years. I've been upgrading both Windows and Thunderbird versions with no major problems. The configuration of Windows 10 + bitdefender 2016 + Thunderbird worked fine till yesterday.