I have the same problem except it is my brights that go blank and I have to use my dim headlights. I have researched it and it is the contacts in the headlight switch in the steering column. I have just posted a post about this and some of the guys confirmed that if I clean my contacts that the problem will be gone and be in the rear view mirror. I will be cleaning mine when the weather warms up. I would recommend you do the same.