Read on for more details on how to install the root Certificate for "The Plateau".

For Internet Explorer, just click on the this link.  When prompted click the button which says "Open from the current location" this should inspire Internet Explorer to offer to install the certificate for you.  Various dialogs will appear on which you accept the default - press Enter.  This should install the certificate for you.  Once this is done you can use SSL to access the Web Interface without being prompted to approve the certificate.  The same should apply to Outlook and Outlook Express, as they share the same sets of certificates as Internet Explorer.

For Netscape.  You're on your own here, as I don't have access to this browser to check at the moment - sorry!