Questions, so are you also running your taillight? The taillight runs off of your front light.

Anyway, it sounds to me like funky wiring issues. Feel free to call us for some free advice - The Bike Hermit is pretty good at diagnosing Dynamo lighting. On another note, have you seen the new Dyna-snap magnetic wire connections - just put them on Bernard - haven't had to use it yet but am pretty excited about not having to yank my wires out of the hub to take my wheel off.