The first time this has happened in 60,000mi - I have MFT Sync 2 - was streaming Bluetooth audio from phone and using NAV, tapped entertainment then NAV on the home screen and sync completely locked up at the home screen. No touch screen response, no response by holding voice button on steering wheel.
I kept driving and was considering pulling off to restart the car but no easy exits. After about 5 minutes I guess a timer must've elapsed - the screen blanked out, Sync restarted and ran disk maintenance. At first Nav was like "SD card not supported" - but after a few more seconds it restored the audio and current route as if nothing happened.
I guess now I really can say I managed to crash every computer I've owned.