OK, let me see if I can describe what happened here.

I was shooting time lapse sequences for Jennifer's street painting last weekend. The sky/lighting conditions were bad - very overcast flat light - low contrast.

I set up the D90 on a stand, actuated the remote interval timer (set at thirty seconds, then trip the shutter, repeat.) Every once and a while I would get one way, way over exposed shot.

In the sequence example below the shutter times are 1/50th, 1/8th, 1/50th.

There wasn't any real change in lighting conditions. It is not repeatable on demand. There is no pattern to the crazy exposure. And this has not happened before. I have not has trouble with this camera before. The camera now has around 50K shutter actuations.

However, the same thing happened perhaps 15 times during the day..shot, shot, shot........shot, way crazy over exposed shot, shot.......shot, shot......

Someone care to explain what happened. Thoughts?