I think there's a frayed wire somewhere causing the hot lead to go to ground, thereby killing the bulb. When the bulb blows, does the high beam side still work? If so, that will help narrow your search. I'm going to say that the harness between the bulb and junction block is to blame because the driver's side bulb still works. Trace your line back, starting at where the bulb connects to the wiring...look for any bare wires and repair as needed.
I had a 53K that kept blowing the headlight circuit breaker. Turns out, it was a bare wire to the license plate light. I spliced in a new wire and that ended the problem!