Hello,

Certain Thunderbird problems can be solved by peforming a Clean Reinstall. This means you remove Thunderbird's Program Files then reinstall Thunderbird. Please follow these steps:

1. Download the latest version of Thunderbird from http://www.mozilla.org/en-US/thunderbird/ and save the setup file to your computer.
2. After the download is complete, close all Thunderbird windows (Click Exit/Quit from the menu button on the right).
   • Windows:
     • C:\Program Files\Mozilla Thunderbird\
     • C:\Program Files (x86)\Mozilla Thunderbird\
   • Mac: Delete Thunderbird from the Applications folder.
   • Linux: If you installed Thunderbird with the distro-based package manager, you should use the same way to uninstall it - see Installing Thunderbird on Linux. If you downloaded and installed the binary package from the Thunderbird Download Page, simply remove the folder thunderbird in your home directory.
3. Now, go ahead and reinstall Thunderbird:
   1. Double-click the downloaded installation file and go through the steps of the installation wizard.
   2. Once the wizard is finished, choose to open Thunderbird after clicking the Finish button.

WARNING: Do not run Thunderbird's uninstaller or use a third party remover as part of this process, because that could permanently delete your Thunderbird data, including but not limited to, extensions,emails, personal settings and saved passwords. These cannot be recovered unless they have been backed up to an external device!

Please report back to see if this helped you!

Thank you.

This is not a problem with the program's installation: the feature seems not to have been built into it.

QUESTION: "Please add a feature that would allow one to prioritize (re-order; move up or down) items that are on the calendar's Tasks list."

Yeah some answers are a little less than helpful.

When you really need to do here is file a bug requesting the enhancement here https://bugzilla.mozilla.org/ But it looks like it is already in the pipeline. But the pipe has a block. see https://bugzilla.mozilla.org/show_bug.cgi?id=412514