1999 Mercury Sable HELP headlights are possessed! TURN ON O

MY HEADLIGHTS ON MY MERCURY SABLE STATION WAGON STARTED TURNING OFF AND ON ALL BY THEMSLEVES TONIGHT. I HAD TO FIANLL UNHOOK THE BATTERY. THE MEMORY FOR THE COMPUTER WHEN UNHOOKING THE BATTERY DID NOT RESET . AND IT CONTINUED TO COME ON AND OFF BY THEMSELVES. MY LIGHTS ARE ON A SENSOR OF SOME KIND AS THEY COME ON AT NIGHT BY THEMSELVES WHEN I START THE CAR AND TURN OF AT NIGHT WHEN I SET THE ALARM AND TURN OFF THE INGINITION. WHAT IS THE PROBLEM IT COULD BE SEVERAL THINGS I THINK. SENSORS, IGNITION,/?? CAN ANYONE HELP THANKS...