I had a 5D MK3 loaded with a sandisk Extreme Pro 32 GB SD card rolling on high end corporate video and lost 7 mins or so of footage of a CEO interview due to a freeze. Luckily I was running as second cam - with primary cam a SONY F-800. It was a serious embarrassment, but not a disaster only because the primary cam saved us. I had another freeze recently while rolling video - again a Sandisk Extreme Pro 32 GB (a different copy from the first one) and a different 5 D MK3!! Not sure what is going on, but all trust is gone. Will not roll a single clip longer then 7 mins or so for fear of losing a massive moment. I have used these cameras extensively for broadcast without problems, for several years since the very early days of the 5d mk2, and love them. Please, Canon, get to the bottom of this!