im not an electrician so this might be incorrect.. but im pretty sure the regulator is for more then your lights??? the blue wire plugs into your cdi from the regulator..but i havent cracked open a cdi to see if it only supports the lighting or if it bridges on to the ignition side also...
cdi's go out all the time without warning... that could be your problem... theres a ton of reasons electical units fail, just test each component and start narrowing it down