Start *Windows'* safe mode with networking enabled - win8 http://windows.microsoft.com/en-us/windows-8/windows-startup-settings-safe-mode Still In Windows safe mode, start thunderbird in safe mode - http://support.mozillamessaging.com/en-US/kb/safe-mode

Does problem go away?

I brought Windows 8.1 up in safe mode with networking. I brought Thunderbird up normally and everything seems to be working. Do I always have to run in safe mode with networking in order to be able to use Thunderbird? Could I backup my folders and address book, remove Thunderbird and reinstall then recover the backups? Not sure if the problem is solved or simply bypassed at the moment. Thanks for the feedback.

> Do I always have to run in safe mode with networking in order to be able to use Thunderbird? No. What you did is a test, which basically just proved the problem isnot Thunderbird. The next step is to determine what is causing the problem. one good possibility is your antivirus program. Which one do you run?

> Could I backup my folders and address book, remove Thunderbird and reinstall then recover the backups? The program and data are in different directories. So backuping up data is good but there is no need for restores.

Suggest you remove the thunderbird program, and the program directory. Then install it again from http://getthunderbird.com/

I run Norton 360. It has been my anti-virus for years and I've not had a problem with Thunderbird before. My wife has the same exact desktop with same Norton and Thunderbird and doesn't have issues. I will try the remove and restore next. Should I do that in Windows safe mode? Thanks.

Today I powered down the PC and came up normally in Windows 8.1. I've started Thunderbird successfully and it appears to be working fine. I made no changes to the program. Who knew? Thanks for all of the help. Marking this solved by magic.

maybe norton decided to behave :)

=magic