I do not understand how much work would it be to just replace the iDrive CIC and let you find out if that solved your problem. If the problem persists then there is a problem with the actual wiring/MOST cables in the car; if the problem goes away then it was the HDD acting up.
Of course, using a customer as guinea pig is never nice. However, that is much, much better than this Mickey Mouse show of talking: of diagnosing, about calling BMWNA, about legal counseling, about "if you do this we will do that". And the car is still sitting there for days waiting for something to happen on its own.
This is absurd.