Went out to my 2006 Cooper S last night and the high mounted brake light only was on.No other lights on.Tried starting the car and turning off the ignition to reset but to no avail.Tapped the brake pedal and the other brake lights illuminated and went off as they should.Just removed it and unplugged it for now.
Any thoughts???? Strange....

 

Any moisture/water issues in the car...
Odd things happen when the BCM , located on the passenger side, gets wet, usually from a leaking sunroof drain.