Yeah, we are currently trying to find out what exactly causes the issue. We know that for some reason the mod sometimes appears to be unable to read the predefined zombie waypoints properly, which causes an infinite loop in the pathfinding algorithm and consequently crashes the server. However, we are not sure why this is happening, so we have not yet been able to resolve it. We asked for some help from the RotU-Revolution developer(s), but it appears we are the first ones to have encountered this problem. So, right now they do not really know what is causing it either. I hope we will be able to find out soon, but I'm afraid it might take a while.