[creeper]

the plastic gear in the headlight motor is stripped. very very very very common problem. you'll also probably notice you can't turn the foglights on without the headlights popping up(for the OP at least).

do a search on google, there's a free fix that works most of the time. otherwise you can pick up a plastic replacement, brass replacement, or whole new motor. i got remanufatured motors from autozone for $70 each, with lifetime warranties. good thing they're warrantied because my 5th one just stripped.