Update 18-12-2006.
This is no longer an issue, with the final release of Outlook 2007. I don't know where it has been fixed, either on AVG or Outlook.
A very dissappointing development is that, Grisoft has decided to discontinue the free edition of AVG.
There is an e-mail rendering problem with Outlook 2007 Beta 2 when used with the Grisoft AVG Outlook plugin. AVG certifies each incoming email as safe. This causes Outlook not to render the message body. Outgoing messages are blank too.
The fix is to disable the email scanner. I found that the message bodies of my pre and post AVG emails are readable.
AVG says this is about MS not following standards, no comments from the Office team yet. Hope this is fixed soon, as AVG offers an excellent free , light weight AV solution.