I am going to try to answer your question. We have mojoportal and many other web sites running on servers within our network. Here is our setup. Say the url is web.myurl.com. The outside world sees the IP address as 216.x.x.x. Our internal dns server reports the address as 192.168.x.x. That is because something with our firewall and internet connection, we can't access anything 216.x.x.x inside our firewall.

Based on what you said with the IP address and the computer name, because you could be using a different IP address for internal users it might be going to a different web site than the computer name (host name) is going to.

What do you mean by does not work? What are you getting and is there anything in the log file? (data/currentlog.config)

That's possible.  What IP address do you get when you do a nslookup?

C:\>nslookup computername

It might not be a DNS problem either.  I could be a IIS website confirmation problem.

what happens when you do nslookup on the web server itself instead of a client machine?

does the iis web site have a host name configured in the bindings that matches the computer name?