I'm in aperature priority and ("C") constant focus" Why are the 11 point focus area (D2XS) jumping around on occasion. I'm not hitting the so called joy stick control in the back of the camera. I should be the one controlling where I want the focus to be in the frame not having the SLR making random decisions.
Also check function a8. When changing aperture in portrait orientation you can select option nr 2 to avoid changing the focus point while using AF-ON. Also check function f1: pushing the central button will reset the focus point to the middle one (unless it's locked).