Hi, recently I bought a second-hand Nikon F90, Everything's fine except the display where the shutter speed values are shown, there's a flashing 'Err' on it, You can still press the shutter button though, and sometimes after you pressed the button the flashing error will disappear then changed to the shutter speed value but usually the flashing error will be back (This before I load a film). I've tried to reset the settings (pushing two "reset" buttons) and change the batteries, still it keeps showing. Oh, and the film counter on the LCD keeps showing number 4 even before I load a film. Any idea what's the problem is? Thank you very much!