Similar things have happened on mine. It was due to the wiper arm coming loose from the wiper motor spindle.

Check if your wiper arm is tightly attached to the wiper motor spindle by trying to move it with the wipers off.

If it does move then open the cover to the bolt holding the wiper arm on the wiper motor spindle and tighten that bolt. <img src="/forums/images/graemlins/kewl.gif" alt="" />