As stated by Brian (blw) above, the "ERR" message covers a lot of errors. One of these is a shutter time self check. The shutter opening time is measured with an IR source and detector. If the measured time is out of tolerance with the requested time, "ERR" is displayed. Given the image problems you are reporting, I would suspect a major shutter problem.
Gary in SE Michigan, USA. Co-organizer of the Southern Michigan Chapter Nikonians membership - My most important photographic investment, after the camera. D4, D800e, D300, D90, F6, FM3a (black), FM2n (chrome) YashicaMat 124, Graflex Speed Graphic 4x5 My Nikonians Gallery & Our Chapter Gallery