I just had that problem with 60D/ADATA SD HC class 10 card. 10 min file of wedding processional is gone nowhere to be found. I can even see what file number is missing. So with continuous file numbering it still recorded it but didn’t save. There must be a way to recover corrupted file or at least part of it if it used the file numbering – it is somewhere. It only happened ones and then camera worked perfectly with same card after I took the battery out for next 48 hours of shooting with little brakes…