I suppose it possible that something else in your home was affected by the power problems, and has become a new source of noise. While that wouldn't really explain why the lights work for the first few minutes, you might be able to do a "breaker box test," and determine *if* there is something else that is misbehaving. I suppose one of your switches could be going bad, too, and causing noise. Does EVERY switch behave the same way, even if it is the only one turned on?