Which antivirus are you running? Some of them cause problems with
Windows Mail over time. Make sure it is not configured to scan emails.
Email scanning in any antivirus must be disabled, for
reasons explained here:
http://thundercloud.net/infoave/tutorials/email-scanning/index.htm
If turning off the email scanning function does not resolve your problem,
do a trial uninstall of your antivirus. If no improvement, you can
always reinstall it. Instead of uninstalling your antivirus, consider
upgrading to Windows Live Mail, because it is less prone to
suffering bad effects from overly aggressive antivirus programs.
http://download.live.com/wlmail
