This is really just information to help people who don't know...

I have a 2001 X5. The key has randomly started to lock the doors. What led me to confirm that it is the key was I tried to get in the car and the doors were locked - with the key on the inside (luckily I was home and I have more than one vehicle). I bought it used (of course) and I only have the one key (of course) but that doesn't matter because I don't lock my keys in the car and I don't lose my keys.

Several days later I was working on the car and I let the battery get pretty low. I stored the key outside the car this time and it locked the car on me again. No big deal this time - just push the button, right? The battery was dead and the locks wouldn't work. That's OK, just put the key in and do it mechanically - except that's electronic, too, on these "fancy" cars. Luckily the hood was popped and I had access to the charging lug.

I've had this car for more than 5 years so it's not like I just got it and started discovering these problems. But it has come on, suddenly, with a vingeance. If I leave this key anywhere near the car overnight, it will be locked by morning. At the very least I am going to give myself access to the positive side of the electrical system from outside of the car. Hopefully this saves someone from the same trouble I had.