This is really random and I've never seen this, but I figured I'd post it. My friend recently purchased a D2X and said the viewfinder was weird...so I gave it a look.
When looking through the viewfinder...what's viewable will actually move with your eye. If you look through a normal viewfinder, what's displayed is static and doesn't move, however in this particular D2X, the entire screen will move as your head moves around...I dont know if that makes sense or not. Once a lens is mounted, the camera works perfectly, however the viewfinder is now partially blocked (looks like a heavy vignette around the edges of the focusing screen) and setting the aperture to F/22 and pushing the DOF preview button will reduce the viewfinder to a pretty small dot (this is the same with several lenses that I tested on this camera). I'm wondering if anyone has any idea what is going on as I've never seen this and am hoping to help figure out what might be wrong?