AS THE FINAL credits rolled for Sofia Coppola's new candy-colored teen-dream film fantasy about history's most notorious poor little rich girl, "Marie-Antoinette," the audience at the Palais du Festival began to hiss like a box of snakes. And then they booed. Booing at the Cannes film festival, at a screening before an audience of a thousand international movie critics and film writers, is never a pleasant way for a director to start the day. While no one in the mob was shouting "Off with her head," the European press couldn't resist the pun. "At Cannes, Marie-Antoinette Guillotined," declared a 24-hour...