I have a Canon 5D mkii running a few different CF cards. When I download the photos to my Macbook Pro (2012 pre retina) and open in photoshop 1 in 4 or 5 photos is totally screwed. Looks like only a quarter of the photo took place and the rest is all purple lines. If I simply plug the usb from the camera into the computer I have not issues. Not sure what the problem is here?