This problem may occur if you have installed Microsoft Internet
Explorer 7.0 and have previously installed the OWA S/MIME control for
digitally encrypting or signing email. You can determine if the control
is installed on your computer by logging into the OWA (at https://ex.myhosting.com/owa), clicking on Options in the bottom-left corner of the Navigation Pane, and then scroll down to the E-mail Security section. If the encryption options are available to you, then the control has been installed.
To correct this issue, you can uninstall the control from your PC and install the new version by following these steps.
From the Start menu, select Control Panel and then Add or Remove Programs.
Locate Microsoft Outlook Web Access S/MIME.
Uninstall it. You may need to restart your PC for changes to take effect.
Next, log back into the OWA and proceed to the Options page. Re-install the latest version of the S/MIME Control from the E-mail Security section.