Loss of Content of Mail Messages in Mailboxes

I was wondering if my problem was related in any way to the discussion "Smart Boxes Empty in Mavericks Mail" but, as no one has responded I'm

guessing that discussion has gone cold or I've entered the wrong thread! So, to start again:

Since I installed OS X Mavericks I am losing content of email messages. I can open received email messages from the basic INBOX but - ONCE I HAVE MOVED THEM FROM MY INBOX TO A SEPERATE MAILBOX for filing purposes - all I am left with is the title eg,

As shown in INBOX:

open it and could see whole content

..then after move to File Mailbox:

open it and everything, apart from title and date = gone and irrecoverable.

Even moving it back to INBOX = content lost.

I've tried all the restoration from Time Machine etc with no joy.

If this is not related perhaps someone could re-direct me.