I purchased this product in November 2009.  in May 2010 one of the bulbs burned and I purchased replacement ones. The replacements bulbs did not work because apparently the actual socket has a problem. I tested the working socket and that seemed to work with the new bulbs but the one side where the bulb burned does not work. I called customer service and the problem is the starter for that bulb (a small device in the enclosure on top) and they said they will be sending me a replacement starter.