What is adequate ram? I am finding for my rather complex profile that I needed more than 8Gb to address the stuttering of the application. I changed to an SSD drive at the same time, but I think it is the ram that is the real clincher. The "system requirements" are basically a copy of what is set for Firefox, but Thunderbird's requirements for smooth running are much higher than the minimums. I was using Thunderbird on a 3Gh processor with 8Gb of ram with the typical slowest we can get away with dell hard drive and it stopped and started like city traffic.

Recent versions have changed much of the mail fetch process to multi threaded so it is no longer a serialized get mail, multiple accounts access mail simultaneously. This does appear to tax some of the anti virus products out there, with you still using windows 7 it is probably impacting your computer speed in the order of a more than a 10% slow down. Adding to that the fact Thunderbird has never been terribly fast in doing most of it's mail fetch actions is leading windows to think the program is hung.

I still see occasional stops, where the program does appear to be locked for a few seconds, cause in my case not investigated. It is not slowing / interrupting enough as yet.

OK, maybe it is some sort of slow execution, but I just don't see the evidence for that elsewhere. The only thing really is Firefox as I said. For some time many random tabs would just not load at start up. probably more so pinned tabs, but even opening a new tab after start up could be dicey. Recently changed to Chrome and that runs very well. My RAM is 16GB, the processor is i7 about 3.2GB, running an SSD. It is not slow and responds in other ways quite well.

The auto updater has screwed up some of my setting and glitched TB Performing a "Clean" reinstall over your existing installation. 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).
3. Run the setup file downloaded in item 1

Hope this solves your problem.

Hello chuy1

I tried your suggestion. Reinstalled TB directly over the existing installation. Nothing changed, the same dialogue box appeared as before at start up. At this stage I think I will just live with it!

Crazy as it may seem the following did work for another person who was also using Win7.

Start *Windows'* safe mode with networking enabled

• https://support.microsoft.com/en-us/help/17419/windows-7-advanced-startup-options-safe-mode#start-computer-safe-mode=windows-7

Still In Windows safe mode, start thunderbird in safe mode

• https://support.mozilla.org/kb/safe-mode-thunderbird

It is possible this should work, so then whilst computer is still in 'safe mode with networking', restart Thunderbird normally.

Finally, restart Computer normally and start Thunderbird normally.

Please report on results.

Nuclear option? ... "Clean Install" Steps to performing a Clean reinstall modified from "Common Responses":

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).
3. Backup your profile. The old profile folder can be added with these instructions. Typically C:\Users\{Account}\AppData\Roaming\Thunderbird\Profiles. More info on backing up and restoring profiles is also available in the Moving Thunderbird Data to a New Computer and Profiles support articles.
   • Windows:
4. Delete the Thunderbird installation folder, which is located in one of these locations, by default:
   • Windows:
     • C:\Program Files\Mozilla Thunderbird\
     • C:\Program Files (x86)\Mozilla Thunderbird\
     • C:\Users\{Account}\AppData\Roaming\Thunderbird <- I added this step. See WARNING: below
   • 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.

Re-install Thunderbird using the file downloaded from step 1:

1. Double-click the downloaded installation file and go through the steps of the installation wizard.
2. Once the wizard is finished, choose to close Thunderbird after clicking the Finish button.
3. Copy the backed up "Profile" DATA back into C:\Users\{Account}\AppData\Roaming\Thunderbird\Profiles
   • Thunderbird creates a NEW alpha numeric folder under profile. I keep this folder and COPY the OLD alpha numeric folder <i>contents into the <b>NEW alpha numeric folder <i><- I added this step.
4. Open Thunderbird

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!

I hope this helps.

Many thanks for suggestions, but I may just have solved it!

Hunting and fiddling around I stumbled upon a website talking about problems opening applications. The one that seems to have solved this so far is to run Thunderbird in Windows 7 compatibility mode! Because of course, the OS is Win7.

Will wait and see if this solution holds up over some days before I celebrate though.