I had similar problem 2 weeks ago (not sure if the same), loud grinding almost like screeching noise comming from the driver side engine compartment. The vehicle would seize up during start or stall while driving. Dealership diagnosed problem as bad alternator/generator, it was replaced along w/ v pulleys and running good since.

Its the ABS sensor, you might wanna change it ASAP, because its gonna happen again. You can disconnect it if its happening constantly... untill you get to the nearest bmw dealership.

My friend your problem sounds like you have pressed the HDC switch by mistake, I have had a similar problem and found that I had the switch pressed.

I agree with fernor, i have also done this in the past and it can be quiet scary if you don't know whats going on. Turn your hill decent control on and see if this replicates your simptoms.

I had the same be4 :confused:

Drive with your windows down and try to locate where the noise is coming from.
I have the same year and model.
Mine was making a grinding and rattling when in gear with the brake applied.(red light) I ignored it for a day and the tranny went.
Get it to a dealer if under warranty or a good qualified independant if out of warranty.

My non dealer mechanic charged me 5200CND for a replacement with 2 year guarantee