From NASA site: "The Curiosity team also continued to downlink high-resolution black-and-white images from its Navigation Camera, or Navcam. These individual images have been stitched together to provide a high-resolution Navcam panorama, including a glimpse of the rover's deck." I think those black squares are missing or corrupted images. Sorry, but could not ressist to make fun of those conspiracy theories. There arent that many people to belive in them, are they?