Croteam just released a small fix for the recent released demo, The Second Encounter. This 'fix' is for people that run a dedicated server. Here is a spot from the article:

So, we are releasing the FIX for the scripts needed to run dedicated servers for the SSam:SE Demo. This fix is ONLY for those who are running dedicated servers. IF YOU DON'T PLAN TO RUN A DEDICATED SERVER, YOU DON'T NEED THIS FIX. Head over to Croteam for full story and download!