Hi I have the same problem:
I have a Centos 5.1 O.S. and my computer has a 64 bit processor (not 32 bit).
All thunderbird versions I tried (1.5xx, and 2.0xx) show the same problem, I can't read my own mails.
It appears that the header is somehow screwed up and thunderbird thinks that the message is deleted (The message exsists in the Inbox file but thunderbird doesn't show it).
When im sending a message to other people, those with thunderbird report the same problem and those with other email programs (like pine, gmail) can read it without problems.
I think it must have something to do with the 64 bit compatibility, does anyone here have any suggestions?
here is an example for a screwed up message that appears in the Inbox file (In the Inbox file the beginning of this message starts right after the previous message without a space line. I don't know if this is significant or not):
Thu Jan 31 18:40:32 2008
X-Spam-Checker-Version: SpamAssassin 3.1.7 (2006-10-05) on wise.tau.ac.il
X-Spam-Status: No, score=-3.8 required=6.0 tests=ALL_TRUSTED,AWL,BAYES_00
Received: from gamma.tau.ac.il (gamma.tau.ac.il [126.96.36.199])
by wise.tau.ac.il (Postfix) with ESMTP id 26FFDA33C3
for <email@example.com>; Thu, 31 Jan 2008 18:40:32 +0200 (IST)
Date: Thu, 31 Jan 2008 18:40:32 +0200
From: Omer Bromberg <firstname.lastname@example.org>
User-Agent: Thunderbird 188.8.131.52 (X11/20071031)
Subject: screwed up message
Content-Type: text/plain; charset=ISO-8859-1; format=flowed