Occasionally, Extensions may cause problems with Thunderbird, including reduced stability and performance. If you encounter problems relating to parts of the mail client no longer working, the mail client not starting, windows with strange or distorted appearance, degraded performance, etc., you may be suffering from Extension or Theme trouble. Restart the mail client in Safe Mode. On Windows, start using the "Safe Mode" shortcut created in your Start menu or by running thunderbird.exe -safe-mode. On Linux, start with ./thunderbird -safe-mode and on Mac OS X, run:
cd /Applications/Thunderbird.app/Contents/MacOS/
./thunderbird-bin -safe-mode
When started in Safe Mode all extensions are disabled and the Default theme is used. Disable the Extension/Theme that is causing trouble and then start normally.
