Ohk, I couldn't resist.. Even this is a very very nice riddle... :D Never mind the Halloween part.. :P :D

So, you've angered the spirit of Halloween by failing to revere the Great Pumpkin, and now a curse has befallen you. On the walkway home, you find a Ward of Seven Jack O' Lanterns arranged in a circle. If midnight comes and any of the seven are still lit, a dark reaper and seven dark horses with seven dark riders shall visit thy abode. They shall surround thy domicile and, while circling it, they will proceed to pelt thy dwelling with eggs and cream of shaving. And come morn there will be a great mess to be reckoned with. So you better get those lanterns out.
Unfortunately, you quickly discover something odd about these lanterns. When you blow out the first one, the lanterns on either side extinguish as well! But there is more. If you blow out a lantern adjacent to one that is extinguished, the extinguished one(s) will relight. It seems that blowing on any lantern will change the state of three - the one you blew on and its two neighbors. Finally, you can blow on an extinguished lantern and it will relight, and its neighbors will light/extinguish as applicable. Frightened by the sound of many hooves, you try to clear your mind and solve this puzzle....