Page Six reports that Brittany Murphy has become a major diva on the set of her new movie

Brittany is currently shooting "Across the Hall" and has been making outrageous demands.

A source said, "She's extremely difficult. When she gets to the set, it comes to a grinding halt. She's so hot and cold, you never know."The source also said Brit makes assistants remove all the crusts off her diagonally cut peanut butter and jelly sandwiches. "She needs one every hour. It's painstaking - her assistant takes about a half an hour making each one."