X-mas lights...

Yeah, apparently so many people were driving past the house to see the lights that it was causing traffic problems. Didn't hear about an accident but from what I understand, he did take it down because of the traffic.
 
Actually, what happened was that an accident took place elsewhere, but the congestion around the guy's house caused the ambulance to be delayed, so he shut down the display.

Source: Snopes.com (I think)