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\

1. 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.

Well I did that the last time, but guess it didn't fix it last time. I tried again this though, but can't tell if it works before next update, although the installer STILL gets stuck checking addon compability. That one I can cancel though. I suspect I will have the same issue again next time as I have had it for several updates now.

I am running Windows 8.1 Pro x64, just in case that info is needed.

next time it happens boot windows into safe mode with networking and try the update again. While is will probably be 6 weeks before the next security and stability release just post onto the thread again with your results from safe mode.

Okay I'll try that and return here with the result when it's time.