My 325 CI is literally in the shop now for this issue! It was annoyingly intermittant, and of course wouldn't happen when I brought it in to the dealer.
I made a point of running it through every concievable lock situation and then discovered the problem: when the car auto-locked passing 8 mph, the latch would fail and become unopenable. I brought it in, and was able to demonstrate it by driving no further than to the curb, and the shop forman simply determined to replace the door latch.
Of course, what really was of concern to me was what would happend to my girlfriend or son if we got in a crash, I was passed out or dead and they would be unable to get out of the damn car! To me that is the biggest concern.