Disable the email scanning feature in your anti-virus software. (For example, in AVG, uncheck certify under the email scanning settings.) You'll still be protected by its other features and by Outlook's own security, and new messages shouldn't lose their bodies. Messages you've already received, though, can't be repaired.
--
Sue Mosher, Outlook MVP
Author of Configuring Microsoft Outlook 2003
and Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers