Apple Mailbox appearing in trash and in inbox This morning I got the message "An error occurred while moving message to mailbox (null)".

I discovered my entire mailbox is duplicated under Trash and under my Inbox. Anybody got any ideas on how to repair this?
Are you using an IMAP account? If so, remove the account and add it again so it downloads your mailbox entirely from the server. 

Did you find the mailbox tree in your Mail.app trash or in you OS X trash?