Answer to: "err" message on the display, the answer is not clearMy D80 had a similar problem, displayed Err, wouldn't auto focus, hear the shutter no image saved. The images on the card could still be viewed. The manual states on page 132 that Err blinking is a camera malfunction and to send it in for service. According to the authorized service center in my area the problem was; Err Not Working. Mirror / Box Operation Repaired Aperture Mode / Operation Repaired Checked and cleaned. Replaced part, Aperture Control Unit $32 plus 2.48 tax. $259.48 total cost with labor. I can't say if this is a solution for you, but I was happy to pay for the service, these guys were very old school and I was glad I could support a small shop.