I own a 2000 Buick Lesabre Custom. It just developed a problem. The interior lights stay on whether the engine is on or off. Normally, when you open a door the interior/courtesy lights stay on until you put the key in the ignition, then it goes off. It now stays on. By interior lights, I mean the overhead lamp (dual) and the lights in the front and rear door panels. Nothing on the dash remains lit and I don't get a problem showing up on the instrument panel. The lights go off after the 10 battery saver timer. I recently had a problem with a rear door window power window (which is disconnected while waiting on parts). What could be causing this problem?