I have been using my D300 for 7 years without a hitch. Last month I was changing my 18-200 to my 70-200 2.8 for more light and when I switched back my 18-200 I could no longer take photographs. I tried the 70-200 again but the same error code showed up in the top screen (no lens) I took it to an authorized Nikon repair shop in St. Petersburg FL. and after three weeks he tells me he doesn't have any idea what's wrong with it and to send it directly to Nikon Factory. Any ideas?