'02 Buick Regal high beam lights work only intermittently

While driving at night on the highway sometimes the high beam lights go out. Sometimes they come back on for a little while. When this happens, I cannot even switch back to low beams right away. After a few minutes of toggling the switch, the low beams come back on and will stay on. It’s very frightening when the headlights go off suddenly. My mechanic things it might be a fault switch (will cost approx. $600 to replace it), but he isn’t completely sure that’ll end the problem. Any ideas?

Had that problem with my Riviera except low beam. They went out because a short overheated the circuit breaker. As soon as the breaker cooled off, they worked again. The cause of the short is the problem. I disabled the twilight sentinal and that solved it for years and then started again. I suspect it could be either the on off switch itself or the stalk. If they are all on the same stalk, then not much else to do but replace it.