Why do I get an error message, "Unidentified Image?"

When I try to view the photos, I get the error message, Unidentified image. I have tried replacing the memory card, but that does not help. The manual says it is because of a problem transferring the photo to a computer, but I have not tried to transfer the images to my computer. When this happened, I had some images on the memory card, but then it just stopped recording them.