After a bit of research in the manuals, I can find nothing of help. But given the delay you experience before the voice message, it may be the telematics communications unit (TCU) going through all of its start-up connectivity and not finding something it should. The telematics and electronics in this vehicle are incredibly interconnected, very complex, and sense and/or control almost every aspect of operation (I learned there is a steering angle sensor behind the logo in the center of the steering wheel. It senses the position of the front wheels to create the guides on the rear view monitor screen). Some things you might try, if you haven't already:
1- are all fuses good and fully inserted?
2- do you have any information feeds through CARWINGS? If you have something from a website or RSS feed, are the addresses correctly entered or have they changed or been cancelled?
3- do you, or really your car, get a good cellular signal in the places you start the car?
If none of the above is at issue, you likely have an electronic poltergeist lurking inside. The dealer's CONSULT diagnostic device has the best chance of finding the glitch and leading to what should be a warranty repair. This was suggested by others and I would agree.
Good luck, and let the forum know the outcomes please.
2012 SL Super Black
Registered to order: April 20, 2010
Ordered: December 6, 2011
11,900 miles, 10 bars showing, 75% SOH, 49.80 Ahr