Boasting the likes of Jennifer Aniston, Shirley MacLaine, Kevin Costner and Mark Ruffalo, the all-star cast of "Rumor Has It ..." is pretty much all that this tolerable, but not particularly funny comedy has going for it.

The wacky premise centers on disgruntled journalist Sarah Huttinger (Aniston) who discovers that her mom and grandmother (MacLaine) both slept with the same man (separately of course). With some amateur sleuthing and finger-pointing, her worst suspicions are confirmed: these real-life flings inspired the 1967 film "The Graduate." Undeterred by the inherent ickiness of the situation, Sarah makes it a multigenerational affair by tracking down the man (Costner) and yanking him into bed too. Oh yeah, and there's also stuff about finding herself and learning to appreciate her fiancee, the man she so blithely cheated on with her ill-considered fling.

Veteran director Rob Reiner was brought in at the eleventh hour to replace writer T.M. Griffin at the helm, and it shows. All previous footage was scrapped, making that scenes are just thrown together in order to get to the meaty "what if" scenario of the story. Because the premise is so involving, Aniston gives a quickie voiceover rundown of "what happened before" to get audiences unfamiliar with "The Graduate" up to speed. "And that's how the deepest, darkest secret of one Pasadena family became immortalized," she intones at the conclusion of the four-minute exposition.

Reiner also breaks the all-important "show, don't tell" rule. Instead of letting us see how out of place Sarah feels in her affluent, country club-friendly family, he has Sarah whine about how she's the only Huttinger who doesn't play tennis or drive slowly. What a tragedy. If it weren't for Aniston herself, Sarah would be a very difficult character to sympathize with. Her identity crisis simply lacks weight. She also treats her fiancee Jeff (Ruffalo) pretty shabbily even though he accommodates her various neuroses and -- God forbid -- gets along with her family.

With all this quirky dysfunction, Reiner should be in his element. Since this was a rush job, however, "Rumor" falls far short of the charm of Reiner's "When Harry Met Sally," "The Princess Bride" or even "Stand by Me." It's also a missed opportunity for a cast that gamely delivers wannabe clever lines like "Life should be a little nuts or else it's just a bunch of Thursdays strung together." And then there are the less subtle attempts at irreverence that has America's sweetheart muttering "blunt testicular trauma" to herself.

Because of Aniston's recent real-life dramas, her hurt, vaguely lost look will elicit the proper sympathy from the audience. She's the everywoman that men and women love, which adds a grounding element to the film even if her character has lost control. She's a formidable foil for MacLaine's Katharine, whose idea of grandmotherly comfort is an offer to "put on a pot of bourbon." Although she gets the most laughs, Katharine comes dangerously close to being a caricature that's so ballsy, she even grabs her crotch in the film. I'm still trying to banish that image from my mind.

Costner as Beau Burroughs -- the supposed inspiration for "The Graduate's" Benjamin Braddock (note the shared initials) -- is affable, but not convincingly charming enough to lure women to sin against their better judgment. While Costner does nothing wrong, the almost mythical quality to his character makes him inaccessible. In contrast, Ruffalo is all-too human, easygoing, dryly funny and lovable as Jeff -- the perfect cuckolded guy you root for. With "Just Like Heaven" out this past year, Ruffalo's romantic leading man career seems assured.

Like a rumor with lots of flash and very little substance, "Rumor Has It ..." is intriguing because of its cast and slightly pervy premise, but will be forgotten once something more sensational or important comes along.