I have the advantage of viewing the game from 2 computers when my son gets on and plays. I noticed at one point during a death match in the underground train station parts of the graphics disappear when crouching. I didn't notice it doing such on any of the others but I haven't gone through and tested each for it either. I asked my son who was playing on our home pc to do the same and the same results were produced.
Autumn (Gun Slinging mama)