Oh dear....
My 6D is less than a year old and has developed a fault.
I down loaded the SD card after a day at the Clipsal 500, and replaced the card back into the camera.
When I switched it on the next day the message came up "No card in camera". Oh really?
OK....I have checked out the card in another camera and it is fine.
I have tried several other cards in the Canon and the same msg appears.
Reading a few camera chat sites, it seems that this is not an uncommon problem for this model and the 5D as well.
Anyone else had this happen?