Well, when my voltage reg went bad, it fried my bulbs.... I put a meter on the front headlight connection to check voltage. It was good at idle, but as soon as I revved the motor the voltage shot up.....much higher than 12V. I believe all the regulator does is shunt some of the power at the higher RPM's to keep voltage constant If it went bad, it should blow your bulbs out.....
Have you checked the voltage at the bulbs with the motor running? Maybe you have a bad wire in the headlight circuit? or a bad switch? I would check voltage at the lights first, then at the switch to make sure there is not an open connection anywhere.