the same thing happened to me. half of my string of lights was not working. the answer ended up being very annoying and simple. it seems my Nova outdoor lights are susceptible to water infiltration from where the wires enter at back, the water freezes and Severs the contact, causing the lights to go out. it was simply a matter of finding the bulb that was no longer in contact, melting the ice( by blowing into the socket while on my ladder to melt it) and then pluging the light bulb back in. presto we have light! hope this helps and the stops at least one person from Cutting apart their lights. merry xmas!