My D2x is on the blink. The diaphragm-actuating lever just inside the lens mount isn't moving in sync with selected shutter speeds to provide the correct aperture.
With both AI/AI-S and AF-S lenses I notice extremely haphazard control of lens diaphragms, alternately not being opened fully, and sometimes sticking part-way open after the shutter is released. When this happens, the camera gives an 'ERR' code in the top LCD. Iif the lever happens to allow the iris to return to fully-open, no error code is displayed. In all cases extreme over-exposure results.
Shutter actuations are at 41,000, and the shutter appears to be working correctly.
I'm tempted to think that the actuating lever may have been bent or damaged somehow, and that a relatively simple DIY repair might work (Update: This doesn't look like the case - there is no obvious external damage.) I have notified Nikon, and will probably send the body in for a repair estimate (lower end of possible repair range is around $300).
If you've had, or heard of this problem, I'd appreciate any feedback.