All Lights go out for 4-5 seconds

When I bought this Monte carlo 03. And the first time I took it home was at night and just 2 blocks from my house, the lights(all lights/in&out) Went out for a few secs. I took it back to the dealship and they said it senor mod, and they took care of it. About 9 months later it happen again!

Any Idea's? I am all out. Thanks.

I just got back from town and it happen again. lucky I wasn't on the highway. But I did find out that the Dash&radio lights stay on when this happen. I guess I didn't realize this, because I freak out the first time.
But I did try to pull the light knob all the way out from auto, no change.
I Couldn't t tell if any other lights beside the headlight went out.

I also have a problem with the hi/lo beam lever, I have to pull back hard to get the high beam to work. Could this be the problem?