I've just installed a larger hard drive and decided to try AVG Free antivirus instead of Norton I had previously. Everything seems fine except that about half of my emails only read "No virus found in this incoming message. Checked by AVG Free". All the rest of the message content has been deleted. I've uninstalled AVG and then reinstalled it but the same thing happens. This can be a big problem when I loose important emails.
Open AVG Control Panel (D/Click System Tray icon) > D/Click Email Scanner > Plugins > Configure > Email Scanning - Un-check Certify mail under the Incoming Mail > OK