I first read about this issue at Fred Miranda.com and elsewhere:
..After 2 shots 1/4 of the image was black on every frame (shutter partially stuck).
...If the camera is tilted at all so that the base is closer to the ground than the top of the camera is the shutter jams every time now.
...Shortly after this the shutter of my 100s got stuck and I wasn’t able to take any picture with the camera anymore.
Fixing it surely means the camera has to be returned for major repair. I am going to be on the lookout for the problem and if it occurs, back it goes—I’m not about to pay $6K for a camera and then wait for a repair.
The workaround is to use the electronic shutter, but that would be a very temporary solution, and it’s a bad idea for handheld work.