ClamXav which found 4 problem e-mails in my junk folder all of which had never been open and I quickly trashed. But the problem continues.
This won't help with your problem, but never move or delete e-mail files manually or allow your AV software to do so. This will corrupt your mailbox index which could result in additional e-mails being lost. More imprortantly, if you have an IMAP account or a POP account where you leave messages on the server, those same messages will just be downloaded to your computer again the next time you check for new mail. Always delete e-mail from your e-mail client application. If this it's a g-mail account you will need to take an extra step of using webmail in your browser to permanently delete any e-mail.