Perhaps just prevent you anti virus from scanning your Thunderbird profile folder while Thunderbird is running. Or place the profile in a stable location (cloud syncing causes issues, using document folders can be an issue, streaming backups cause issues)

Both my email accounts apparently fixed themselves the last few days with all my messages showing up when I open the email. Before that, all or some of the emails would show up on my gmail account but never appeared on my charter account. When I repaired the gmail account the messages would always appear new messages on the bottom so I had to click the arrangement button, but the charter account always appeared with new messages on top. What in the world was going on?