Can anybody tell me whether my 17-55 2.8DX, or D2X is at fault here...
or whether this is a common problem. Using autofocus, my camera is
unable to get correct focus on a chosen point at 17mm; it appears about
sharp in the viewfinder (very hard to judge at the wide end of course),
but when I lock the focus and zoom in it is easy to see the camera is
just out. From about 20mm and up, the problem disappears, but the only
way to get a correct focus at 17mm, is to zoom in, focus, lock focus,
zoom out, and shoot. I don't seem to remember this was an issue on my
D1X with the same lens, but I can't be 100% sure. So, is there a
problem with my D2X, or has the lens developed this fault?

Many thanks for any thoughts.