Today, I cannot get on the client's proxy server using FQDN, but only Internet Explorer. Well, if you know, if you cannot get proxy setting working on IE, everything else will fail miserably, example, F5 VPN client, Live Messenger, and the works.
Freaky thing is that, Firefox still likes the proxy using FQDN.
What to do? Had to switch to IP address of the proxy server now. And before you tell me "can you resolve the FQDN name by using PING/NSLOOKUP?", and answer is yes, yes and yes. Other than IE, everything else recognizes the FQDN of the proxy.