Hello,
What format are the images in? JPEG?
Perhaps the photos which you cannot view on your PC are RAW image files, but which can be viewed on your camers...
...depends whether your camera supports RAW image files and whether someone set this as the picture format.
...just an idea :rolleyes:

.
I was gonna say data corruption but your camera can view them properly...so it's probably either a file format problem, or corruption during data transfer (but not data corruption on the card).