Thanks, that is good information. I will have it checked out.

I am late to this party and wonder if anyone can update the group on your causes/solution...

My 2006 X5 MT with 138K miles with H7 halogen low beam bulbs.

- At red light (behind another car), 6:30AM and was dark, HL switch in "Auto".
The low-beam lights turned off by themselves, then when I drove, they turned back
on.

- Arrived at work and parked in underground parking lot, when I stopped the car
(engine running), the low-beam lights turned off again. I left the engine running and turned the HL switch to "On": no change, the low-beam lights are still off.

- After a day at work, during trip going home, it was no problem.

- I understand intermittent problems are difficult to diagnose.

But any suggestions?

For me it was caused by the alternator. Only a few days after these symptoms the alternator failed completely.
Replaced it and the fault never reappeared.