Odd problem with linux.

I have this odd problem with linux. I am trying to run a MUD server, but when I start it I get the error: "gethostbyname long-cryptic-hostname-of-my-comp :no such file or directory" long-cryptic-hostname-of-my-comp looks something like 09-21-a8-01-9a-b7 etc (could it be my mac address. It has been so long since I have seen one that im not sure what it looks like). I would check, but im not at my server ATM. I also cant print, without getting the same error. However, when I unplug my network connection and reboot, and stay offline, all works perfectly. I am running RedHat 7.3. Any ideas?