What is your anti-virus software?

Spectrum.

I thought spectrum was a mail and internet provider, not an antivirus product.

It is included in the package

I would start by creating an exception in the antivirus program for scanning in the Thunderbird profile folder, just because it is good practice. Please also provide results for the following test on your system which may assist in defermining where the issue lies. * 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]

I do not know how to do what you are talking about

re: Anti-Virus: I think Spectrum may be using F-Secure (possibly they call it 'Spectrum Security Suite'). See if the info at this link helps you to exclude your Thunderbird folder which contains all profile data etc from scans. * https://help.f-secure.com/product.html#home/total-windows/latest/en/task_13205052E3D44C44BA2491A55A7F818F-latest-en Your Thunderbird folder containing profile etc is likely to be in this location assuming you are using the default location: * C://Users/user name/Appdata/Roaming/'''Thunderbird'''