In CoD 5 with the 1.4 patch do you see The server is running the mod MOD/NAZI_ZOMBIE_ You need to load the mod before you can join demo.
If you have seen this when trying to play a nazi_zombie_mod with the Call of Duty:World at War patch 1.4 then you are not alone. Many people have seen this and so far as I know no one has a fix..least till now.

I was on the phone with a very good friend that I often play CoD5 Nazi Zombie. He said that he and another player could not play nazi zombie mods after updating to the 1.4 patch. I had not tried it so I jumped online and got with him teamspeak.


After some trial and error I was able to determine that the name of the mod has to be six characters. The includes the underscore _. So if the name of the mod is nazi_zombie_thisiscool you would have to shorten the name by getting rid of "cool". Then the map would play. Simple fix right or so I thought.....My friend came up with the idea if someone took out the first few characters and someone else took out out the last few of the same map would it work.........and the answer is yes it will. We tried several different combinations and finally came up with the easiest fix.



THE FIX IS RIGHT HERE
In the end we simply took off the nazi_zombie from the map and everything worked fine. So if the map name is nazi_zombie_thisiscool Just take off the nazi_zombie in the name of actual folder. We tried single and co-op online with a couple of maps and ran into no problems. Another plus is that all maps show up in alphabetical order.

as of yet i have not came across this problem, but anyway cheers for letting us know for future purposes