BMW 3 Series cutting out

Driving on the motorway Between 65 and 70 miles an hour, the engine cuts out with no warning, All lights on the dashboard go out, my indicators also stop working So I couldn't signal to pull over. Once I'm on the hard shoulder I tried starting the car again, There was nothing no ignition lights nothing exocet the red airbag light, the car seemed to have died on me, I waited a couple of minutes turned the key again and voilà ignition lights, So I started the engine and drove off, a quarter of a mile later the same thing happened again. This happened to me four times in the space of a mile and a half. It now happens no matter what speed I'm driving, and is now doing it when sitting at traffic lights or at junctions, This is getting so embarrassing can someone pleeese help.

Also a Couple Of times recently all the ignition lights have flashed up whilst I was driving.