No idea! You have supplied so little information that there is nothing to even formulate a guess from. Could you please do the following? # Open the menu '''[[Image:Fx57Menu]] > Help > Troubleshooting Information''', then click '''Copy text to Clipboard'''. # Go to https://pastebin.mozilla.org/, paste the clipboard by right clicking in the large text area, select paste from the menu, change the retention period to expire in 28 days, use the '''Paste Snippet''' button to create a page containing your info, then copy the resulting URL (address) of the page created. # Open a reply to this post, and paste the URL to your troubleshooting information you just copied. # Please also provide results for the following test on your system #* Does Thunderbird work as expected in [[Troubleshoot Mode Thunderbird|Thunderbird troubleshooting mode]]? #* Does Thunderbird work as expected with your OS started in '''[http://en.wikipedia.org/wiki/Safe_mode safe mode with Networking]'''. Instructions for each operating system: [https://support.microsoft.com/en-us/windows/start-your-pc-in-safe-mode-in-windows-92c27cff-db89-8644-1ce4-b3e5e56fe234 Windows 10/11], [https://support.microsoft.com/en-us/windows/windows-startup-settings-including-safe-mode-7f31dcea-6427-0ba0-ec1b-729a56321cd3 Windows 8], [https://support.microsoft.com/en-us/windows/advanced-startup-options-including-safe-mode-b90e7808-80b5-a291-d4b8-1a1af602b617#start-computer-safe-mode=windows-7 Windows 7], [http://support.apple.com/kb/ht1564 OSX]