The switch that controls the light may be defective. For instance, a very slight, maybe even unnoticable, vibration could possibly cause the inner swith mechanism to connect/disconnect the flow of electricity. Be sure to TURN THE POWER OFF (You already knew that) and replace the switch, making sure the wires are connected properly, to the right places on the switch and also tight enough to stay securely connected. In fact, the problem MAY BE a loose wire on the switch installed now. Be careful. Hope it helps. Big John