Interesting. The house is only three years old, so I'd be surprised if there was some sort of fault with the internal wiring (but then again, you never know). Another consideration is that I'm using one of those 3-prong to 2-prong adapters to plug the power string into my crappy extension cord. Since these types of adapters (i think) effectively removes the ground from the circuit, might this be the root of my problem?