i have been using ML for few months now without any problems. but last weekend at a shoot the camera wouldent start. i shot some video, changed a card, shot some more, turned the camerara of and after that i couldn't start it. the first card was a sandisk extreme 16GB 120MB/s, the second one and and all cards i shot the rest of the day with were sandisk extreme 32GB 120MB/s. as I put a second card in also with ML on it the camera worked fine.
as i came back home i pluged the card into a cardreader and saw that there was nothing on the card. the name of the card chaneged, usually the name is EOS_DIGITAL but now is said EOS_DEVELOP. luckyly i recovered all the footage, but my camera still doesn't work with this card.
again, all my cards had ML installed and all of them were formated in camera before the shoot.