I have noticed on a few occasions that the navigation screen on the 2014 M6s sometimes fail to start/display. I have had to turn the car off and on and then it works, however, this past Friday, I restarted the car three times on my way to work and the GPS screen never came on after hitting the NAV buttons. On my return trip home at the end of the day, after the car having been parked for 10 hours, it worked again. What's the deal with this issue? It has happened the same on my two sixes. Same thing with displaying or reading (playing) messages on the Phone-Messages screen; messages download but can't open them or have them played out loud. What's the fix?