The issue is due to database corruption. First see if you can figure out what 3rd party program is the culprit. See www.oehelp.com/OETips.aspx#3 and get rid of your antivirus software and get something more compatible with WinMail such as www.microsoft.com/security_essentials (and under its settings disable the eml file type from being scanned). Then remove your mail account in WinMail. (its a good idea to backup what messages you have -- see www.oehelp.com/backup.aspx#wm). Then compact and repair the Windows Mail database (see www.oehelp.com/WMUTil/) and then add your mail account back again with the proper settings. See if things work then.