While I'm not familiar with the newer cars, some DRL systems operate the high beam filaments at 70% power. Perhaps 70% power isn't enough to trigger the starter for the ballast and the car isn't sensing the draw and thinks your headlamps out. some DRL systems will also keep the 70% high beams to spite turning them on manually. Do you have a ambient light sensing system? (automatic on)

__________________
RIP: 80 300SD
RIP: 79 450SEL
2002 E430 4matic (212,000km)
2002 ML500 'sport'

____________________________
FACEBOOK: PANZER450