A nanny who was fired by Robert De Niro has sued the actor for more than $40,000 in overtime pay. Alexis Barry says in court papers that she was never paid for more than 750 hours of overtime and never took 10 vacation days. She began working for De Niro and his wife Grace Hightower in August 2006, and says she was fired 10 months later after she said she was going to quit. The couple have an 11-year-old son. Barry says she is owed more than $40,000, along with about $496 in expenses. She filed a lawsuit Friday in Manhattan's state Supreme Court. De Niro spokesman Stan Rosenfield isn't immediately commenting on the suit.