SIT-DOWN STANDOFF

JULIA'S MISSING CHAIRBACK

On the set of her new movie "America's Sweethearts," Julia Roberts was anything BUT when someone swiped the canvas back of her director's chair! Julia -- who collects every chairback with her name and movie title -- FREAKED! Angry producers refused to let cast and crew leave the set until the thief handed it over -- but backed down when nobody flinched! Julia's got a new chairback -- and it's under security 24/7.