Lets see what we can work out. I must admit I have no idea, so it is truly going to be "work out" This is information gathering not fixes. So please complete the steps so I can get an idea how things are set up.

Please go to the start menu and in the search box type %appdata%\Thunderbird and press enter. Open the file profiles.ini in Notepad and copy and paste the contents to a reply message here on the forum.

Now go to the Help menu and select troubleshooting information. Copy to clipboard and paste into a reply on the forum this information.

Check your computer. Do you have Microsoft SyncToy installed.

In the search box on the start menu type taskschd.msc and press enter. Is there anything listed there?

Could you post a screen capture of your dropbox window showing the emails? What file names do they have? Just a few not Thousands please. That would drive us both mad.

Hi Matt,

I didn't solve it but I did get the problem fixed. I downgraded to an older version of Thunderbird and then upgraded. It hasn't done it since.

Thank you for your interest!

Chris