Jessica denies on-set tantrums

Jessica Simpson: Method actor? The stacked starlet -- with some help from current co-star Vivica A. Fox -- is rebuffing claims that she's achieved a vexing amount of verisimilitude while playing a dizzy, overindulged actress who joins the military in "Major Movie Star," which is currently shooting in Louisiana. Seems the National Enquirer is convinced Simpson has been channeling her inner diva on the set of the comedy, with a spy alleging she's been "acting like a spoiled brat." Among her purported transgressions: She's tossed "tantrums," kvetched about the steamy southern weather, yelled at her assistants and launched into a "loud," four-letter-filled "tirade" against some wardrobe minions because her costume was "too hot" and making her sweat, a rant that left everyone "mortified." The snitch also charges that Jessica "barely speaks" to Fox, "and insists on eating by herself in her trailer rather than in the tents set up for the cast and crew." But Simpson's spokeswoman is quick to denounce the accusations of bad behavior, insisting to MSN Entertainment, "There is absolutely no truth to any of this." Don't believe her rep? How about a few words from the supposedly ignored Fox? "It could not be further from the truth," Vivica vows to MSN Entertainment from the set of the film. "Jessica is so professional, so down-to-earth. A jewel. She couldn't be more of a team player and a leading lady. I'm grateful and very happy to be working with her." As for the tabloid's talk of Simpson being anti-social, it's simply not so, maintains the actress. "We all get along so unbelievably well," says Fox of the predominantly female cast, which also includes Cheri Oteri. "We talk about what girls talk about. Shopping. Boys. We hang out and celebrate birthdays." What's more, she adds of Jessica, "I've found a new friend." Producer Randall Emmett is equally effusive, calling Simpson "a focused and hard-worker" who doesn't complain, even when doing boot camp-style drills in 100 percent humidity. Previous stories from the set have also been decidedly positive, with a game Simpson reportedly scaling a 40-ft. tower despite her fear of heights, getting submerged in a swamp and talking up the adorableness of her fatigues ("I was surprised at how cute the outfits fit!" she gushed to People). Jess has also joked about her scenes with Fox, who plays her tough-as-nails sergeant: "When she screams, I feel her breath on my face!" (Vivica laughingly assures us the proximity is not a problem because she always has "fresh breath.") The cast, meanwhile, has braved the local flora and fauna while filming maneuvers for the "Private Benjamin" homage. "I've been wading through alligator-infested swamps and walking through poison ivy," co-star Aimee Garcia recently told People. "We've all suffered injuries. It's very intense."