This seems to happen to me only in the hexer servers which is strange, because it doesn't seem like a server script error.
Basically, what happens is 1 or more guys in the server (seems to be only on the opposite team) are always in prone. What I mean is that they can jump walk and run like normal, except on my screen they are constantly prone. And when they switch directions they are looking at, on my screen it looks like they stand up, and then lay back down facing the other way.
I'm not sure if anyone else has had this happen to them, but it's sort of annoying, and even if I try to leave and rejoin, the same thing happens. The only thing I can do is wait it out. Also it only happens some times when I'm in there.