I have had a D300 for about five years or so. This year, I noticed I would get an ERR message flashing on the top screen. This only seemed to happen when I was shooting in long bursts at 7fps. I sen the camera back to Nikon. They sent the camera back and charged me $300.00. There was very little explanation other than the whole computer was replaced. It is now doing the same thing again. Nikon wants to "troubleshoot" over the phone before letting me send it back. Any ideas? Has anyone had this problem? Thanks.