Sometimes this is due to someone unlocking and opening the car without knowing, sometimes it's due to moisture in the BC1 unit making it go nuts, sometimes it just seems to go nuts all by itself. Either way it's a trip to the dealer to get it sorted.
I too have had this problem in the last couple of weeks. Only seems to have started happening since having the heated windscreen replaced, though. I'm hoping the dealer will sort it when it goes in on Friday. By the way, not all dealers seem willing to accept there's an issue. The first dealer I contacted (the one I bought the car from) said that the only thing that could possibly have happened is that I'd sat on my keys and they would charge me to remove the comfort opening, if I wished to get rid of this 'helpful' feature. As the keys were well out of harm's way all night, I knew that couldn't be the case. The second dealer, closer to home, immediately arranged to have it looked at and suggested a number of causes / fixes, including a reboot of the computer.