Trouble on ‘Trouble’ Set? : Take your pick: (a) co-stars Julia Roberts and Nick Nolte got on each other’s nerves; (b) the filmmakers got on <i> their</i> nerves; (c) snoopy questions are getting on <i> everyone’s</i> nerves.

If the rumors of discontent on the set of Julia Roberts’ new film, “I Love Trouble,” are to be believed, the film couldn’t be more aptly named.

Joe Roth’s Caravan Pictures film, which also stars Nick Nolte under the direction of Charles Shyer, is about two dueling Chicago reporters chasing the scoop of a lifetime. Roberts plays Sabrina Peterson, the fresh-faced, no-nonsense cub reporter at the Chicago Globe; Nolte plays city columnist Peter Brackett for the rival Chicago Chronicle, a legend in his own mind who is much more interested in gathering women than front-page news. Peterson’s tenacity and competitive edge ends up reviving archrival Brackett’s burned-out reportage as the two go notebook-to-notebook on a train wreck story that turns into much more--murder, mayhem and a little romance along the way.

But sources on the set say the stars may have taken the mayhem part a little too seriously--and the friction may account for the less-than-sparkling chemistry that some reviewers have complained about.

Those involved in the production say that Nolte and Roberts didn’t get along. They claim tempers flared early on, peppered with a few Roberts tantrums along the way. Roberts reportedly wasn’t thrilled with Nolte’s machismo, so she would deride and insult her co-star. Some on the set claim that he became so annoyed with her attitude that he would do things to agitate her even more. The discord was so intense, the sources say, the two played more to stand-ins than to each other.

Other studio sources insist that any differences on the set were actually between the co-stars and Shyer and producer Nancy Meyers, with the filmmakers making Roberts and Nolte improvise repeatedly on the same line. “It drove them (Nolte and Roberts, in particular) nuts,” says one source.

Sources affiliated with the film say that the bad chemistry between the stars shows up in the film. They point to Disney’s decision to switch gears in marketing late in the game--from romantic comedy to suspense thriller. Quips one competitor: “It’s gone from a Hepburn-Tracy ‘Woman of the Year’ to ‘Pelican Brief’ in a very short time span.” Kenneth Turan, in his Los Angeles Times review of the film last week, said that “the repartee is mostly lackluster” and “the romantic comedy aspects . . . are not especially entrancing despite the star power.”

Disney said the various rumors of rifts are untrue, saying that all involved were “complete pros” on the set. In a “Trouble” press junket, for which Roberts did back-to-back interviews for two days, Disney lauded her performance.

“I wish more stars took a page from (Julia’s) notebook. She recognized selling this movie was her job. She was unbelievably pleasant to people,” said Disney spokeswoman Terry Press.

Nolte’s agent, Jim Wiatt, has said the stars experienced only the typical spats between stars on a set.

Roberts, who is filming “Mary Reilly” in England, wasn’t available for comment. But Nancy Seltzer, publicist for Roberts, Shyer and Meyers, denied the account of trouble.

“Serious publications only exacerbate the problem by repeating these rumors,” Seltzer said. “By virtue of this kind of reporting they give permission to the lesser serious publications to do the same without conscience. I’m greatly saddened by the current trend that journalism seems to be taking . . . that of the business of selling copy instead of the search for the truth.”

Besides, notes Seltzer, Roberts has already addressed the purported rift issue, both in the New York Times, which quoted Roberts as saying she and Nolte “sort of gave each other a hard time” from the moment they met. She went on to say that while Nolte can be “charming and nice, he’s also completely disgusting.”

For clarification on what Roberts meant, Seltzer defers to one of the star’s current crop of magazine cover stories, that in Entertainment Weekly: “We had great, um, high-spirited needling of each other, trying to get a rise out of each other.”