I don't know why, but for some reason, when I went on the serious server, hosting ariana, I could see into the void (the same effect you get from noclipping out of the map area), yet I was still in the map area. I don't know if this is a graphics card problem or what. I was using RPGXCE (not sure which version). I tried ariana in my own private server and it worked just fine. I have a condump of the conversation for verbal evidence and many many pictures of this weird effect, which I will post (the pictures at least. People should ask for the condump, with member security versus non-member perspective).
P.S. There are so many pictures 1) to show the full extent of the problem and 2) because I just couldn't believe what I was, or more correctly, wasn't seeing.
Well, this is just a guess but, you may need to download other maps to get those textures.
No then the notexture texture gets used.
Hmmm no idea if there are multiple releases of the map but maybe thats the problem. If the bsp files are named the same in multiple releases the bsp(mapfile) gets loaded despite the fact that they are diffrent as RPG-X servers run unpure (sv_pure 0).
Multiple things can then lead to what you described: for example different entity numbers for ents screwing things up or an area might have moved but the geometry is of course on its old position in an outdated bsp.