SSL Certificate

A colleague and I recently installed an inhouse server certificate on a Windows 2003 server. The install went fine. The server is used to e-mail alert messages to users in the environment concerning system status. Users can login to the server but cannot e-mail reports. The error messages to the users is certificate not found. We did try to view the certificate on the server to check if it is valid and receive a message indicating, “Windows does not have enough information to view this certificate”. What does this mean? What information is missing? How do we resolve this? Any help is appreciated.