I have a D200 with approximately 59,000 actuations on it. Recently updated firmware to 2.01 (both A and B).
Prior to the update, I would occasionally get a completely black frame when I was starting to shoot, or starting to shoot again after not shooting for a bit (I shoot a lot of horse events/shows, so there is time between classes).
More often than not, the first frame of a shooting session would be 1-2 stops underexposed, irrespective of whether I was shooting manual or aperture or shutter priority. Out of 1,500 images I might shoot at an event, I might get 2-3 blacked out frames, and 8-10 underexposed frames.
Within the past 2 weeks, however, the number of completely blacked out frames is much higher, and occurs whenever I have stopped shooting for any length of time. It's so bad that I whenever I bring the camera up to shoot, I automatically click off one frame since I know it will be either black or underexposed.
I did a portrait shoot this past weekend, and captured about 400 images. Of those, 10-15 were blacked out, much fewer underexposed now...it seems to be moving more toward blackout frames.
I've tried looking it up here and on the Internet, but there's nothing I've found that really describes why this might happen.
It's not just the jpg that shows up on the back of the camera, as I've kept the files and imported them into Lightroom, only to see a completely black frame there, too.