Update Nick and Jess

Nick and Jess
Originally uploaded by Bricks and Stones.

Jessica Simpson continues to insist she and hubby Nick Lachey are not splitting - but are the breakup rumors starting to get to her? The coltish actress is said to be bridling at doing publicity for "The Dukes of Hazzard" with married co-star Johnny Knoxville because she doesn't want to feed gossip that they had a fling.

An insider tells us Warner Bros. execs had to use all their carrots and sticks to get Simpson to do a Premiere magazine cover with Knoxville.

A Warner rep argues that Simpson has cooperated fully with the publicity campaign. Her own rep says the 24-year-old actress readily took part in the shoot with Knoxville and co-star Seann William Scott, though she will do some promotion on her own.

Simpson's PR bomb squad is also defusing a claim that Simpson slept with Knoxville's "Jackass" cohort Bam Margera. Phil Margera, Bam's father, told Philadelphia radio deejays Preston & Steve his son admitted bedding Simpson - and "Bam has never lied to us."

But Bam later told the same deejays that his father "is a godd- idiot. He probably thought you were talking about [something else]."

Jessica's father and manager, Joe Simpson, tells Us Weekly, "[Bam's] father was making a sick joke."