From past experience.. with *cough* fords... You have to train the system to recognise the key again before it will play nice.
In the case of fords, it required the key being inserted, turned to position II while pressing something. 30mins later.. yay it was happy.
I'm sure BMW would do something similar to make sure things were secure. A dealer would definitely know.
Yes... i'm a total car nut! Why else would I upgrade my mower to rev to twice its standard rpm!