Can you imagine the frustration when you have in your hand the world most advanced DSLR camera and the image came out to be totally black once in a while?
I was haunted by this problem for a few weeks. Calling up Nikon drew a blank other than the suggestion that I sent the camera in for a checkup. Fortunately, I found the solution as I was relating this problem to my friend. He suggested that I should reload the firmware. True enough, I came back and reload the camera firmware and the problem is now gone for good.
I posted this so that other people who might experience similar "misbehavior" by your beloved DSLR to do the same... reload the firmware.