Sounds to me like one of your high-beam bulbs is burned out. With the high beams on, each outside light should work (unless you were referring to the marker/parking lamps?). If one side doesn't work, it's the bulb. Your projector headlamps wouldn't have anything at all to do with the light-bulb lighting up...they use the original socket and bulb already on the vehicle...pretty much plug-and-play. Anyway, that's what it sounds like to me. Try buying a high-beam bulb and putting in the side that's not lighting up...figure it will solve your problem. Hope that helps.

Paul