I am having currently similar issues. Every 500 pictures i am having aprox. 1 corrupt file. I hope the shutter is ok. I have currently 43000 shutter actuations. The cards I have been using were formated on a nikon but a different model camera. I don't know if it could be the problem.
I forgot to say that my corrupt file is a NEF. On the camera the NEF seems to be ok, I can zoom in and out and i can see the picture correctly on the camera screen. But if I convert it to jpg on the camera the jpg gets corrupted as yours. If I try to open in CaptureNX2 the program crashes.