So the other day we did a photo shoot at a client's house on a 5D with a new CF card and formatted before shooting. We took a bunch of pictures and then set up in another location in the house. We took test exposures and reviewed them on the camera.

When we got back and went to dump the cards - all of the images from the second location were gone, but everything from the first location was still there! I have no idea what happened - we didn't even change lenses on the camera or open the memory slot.

When we tested it out we were able to capture and download the images without any problem.

It makes me a little nervous for future shoots - I am not sure if it was the card or camera or maybe both. Anybody have any ideas of what might have happened?