this happened to me last night at my local track and i instantly thought about your post. i also run a castle setup. i figured out why mine did it. i borrowed a battery from a friend while mine was charging. his was pretty beat and the bannana plugs that go into the lipo wern't tight anymore and any impact would cause one of them to lose connection and reset my esc. check that out on yours. (assuming you are running a lipo as well that it)