Apache/SSL and FQDN/short names

Hi Folks, maybe someone can help.

I’ve set up a secure webserver on SSL, it works fine using the FQDN as on the certificate, and the CA certificate is in the browsers list of approved CA’s, however, the people accessing it are in the same dns zone, and tend to just type the server name into the browser, this generates the typical untrusted certificate warning.

Is this a problem with the CA certificate setup? with dns not returning the fqdn? Or some kind of browser auto complete config? My google fu has failed…