the turning left when failsafed sounds like you controler is not failsafing to neutral.

I have had the same problem described by the OP on BS2, from what I could gather there was enough noise getting into the speedos they treated it as a valid signal and ran, the noise from the motors and wiring feedback into the reciver and the thing went nuts until power was cut. In my case I solved it by putting a metal box around the Rx. I would recomend trying this if you have not already done so(this made a world of difference for me). Other than that try repositioning your ariel and check you wiring layout for interference prone areas.