I have a Malibu garden lighting system that was "professionally" installed in Dec 2009. The floodlight at the end of the wiring circuit has stopped working. The light works fine when I connect it directly to the transformer, so I don't think it's the light. I get between 10 and 11 volts at the end of the wiring (so I think the light should work) and all of the other lights on the circuit work fine.
(Oh, in case your wondering, the "professionals" no longer return calls.)