Just set up a 10-user LAN with each user using Outlook 2013 linked into an exchange 2007 server. All is well except 2-3 times every day on every machine an extremely irritating message insists on popping up saying "Security Alert - Information you exchange with this site cannot be viewed or changed by others. However there is a problem with the site's security certificate" and we have to click Yes to proceed then it disappears. Any way of getting rid? Most annoying!