Thunderbird error truncating the Inbox
If you received in Thunderbird a message about some “error truncating the Inbox you may need to delete INBOX.msf”, most probably you went to the Thunderbird mail folders, deleted the file Inbox.msf, only to find out that the problem was not solved. Thinking that perhaps there is some writing permissions problem on these folders, I removed the Read Only label. Even this did not help.
The truncating Inbox issue is caused by some anti-virus programs, such as AVG. To enjoy Thunderbird without problems, you need to open your Antivirus application and add the mail folders of Thunderbird to its exceptions.
To find the location of Thunderbird mail folders, go to Tools > Account Settings > Local Folders, and you will see the address of these folders on your disk at the “Local Directory” box. Copy this address and paste it to your Anti-virus list of folders to be ignored by its Resident Shield.
You might face similar problems in other applications too, perhaps in your Torrent downloader. You must do the same, add to the exceptions of your Antivirus the folders where your torrents are downloaded.