Check to see if the Aperture Lock on the lens is in the locked position. If you are using the camera in any mode the camerra will show an error if this is not done.

Oh, on ocation yuo may turn it all the way to the point it shots, but then it moves again and you have the problem again.

Your shutter is "going out" I sent my D1x back to Nikon for repair and they fixed it, cleaned the camera, replaced the LCD screen (all without my asking and did not charge me for the extras) The repair was around 1,000.00 if I remember correctly. After shooting for a few months the camera did the same thing again, I purchased a used body for 1000.00 and the old body is now a backup. If I do not use the backup body much it works fine for about 500 or so shots.
My suggestion would be to send it to Nikon to repair and buy a newer body

The problem may be what the last person wrote, but from my experience it's not the shutter going out it the mirror is sticking open. This is a very common problem with the D70, hopefully your camera is still under the warranty, either way Nikon may fix it for free. I have heard several people say they got it fixed for free, because it is such a common problem with the D70. A warning, Nikon will act like they have never heard of the problem, and request you send it in for a estimate, do as they ask, send it in. They will call you with a estimate and may just tell you it's free this time!

Good Luck,
Chris K

I'll say it's the shutter, but the mirror does indeed remain stuck open as well. In my case, Nikon replaced the entire shutter mechanism. I had it back in a week and all has been well since.