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Feeling slightly adrift after a sad week packed with celebrity passings? What better way to regain a sense that all is right with the world than with a rundown of star spats? Here's the latest ...

You'd think that Chris Brown would want to lie low following his jail-avoiding guilty plea last week for his February assault on Rihanna, but he's said to be seething that he wasn't allowed to participate in the Michael Jackson tribute at the BET Awards on Sunday night.

The embattled singer, who hailed Jackson as "the reason why I do music and why I am an entertainer," was purportedly frozen out of the event at the urging of Jay-Z and the Rev. Al Sharpton.

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"Jay-Z wasn't having it," a source tells the New York Post of the music mogul (and Rihanna's mentor). "He threatened to pull out of the show if Chris was involved, so BET dropped Chris."

That claim is reiterated to the New York Daily News, with an insider explaining, "[Jay] didn't want Chris anywhere near the awards so close to the court's ruling."

The mole adds that Sharpton also "made such a fuss to the BET executives that they pulled Chris," who was evidently seeing red over the decision.

"He's furious," a friend of the volatile singer tells the paper. "BET asked him to perform and waited until the last minute to tell him it was off. He's pretty shocked and outraged right now."

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But before you cue the world's tiniest violin, reps for BET and Brown insist that he was never confirmed for the show.

Meanwhile, is Kristen Stewart learning the hard way why Joan Jett, whom she's portraying in the currently shooting biopic "The Runaways," doesn't give a damn about her bad reputation?

The New York Daily News claims the rocker is so determined to get maximum verisimilitude out of the "Twilight" star that she provoked her into a very un-rock-n-roll reaction.

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Seems Jett's goading caused Stewart to "burst into tears" on the set, although perhaps the actress just got a good look at the tragic mullet she's wearing in the flick.

"Joan just wants Kristen to play an authentic version of herself, so she needled her a little bit too much," maintains a spy. "But she apologized when she realized how upset Kristen got."

The pair quickly made up, adds the snitch, who then oversells their reconciliation by saying, "They're like mother and daughter now."

Moving on from professional conflict to catfights, Anna Kournikova apparently ended up soaked and scraped after a dustup in Las Vegas.

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The New York Post says the onetime tennis hottie was partying with pals at Sin City hot spot Lavo on Saturday night when a random woman at the next table tossed a drink at her.

"She felt Anna was invading her space," relays an eyewitness, who says a "big fight" erupted, complete with screaming, shoving and clawing, which supposedly left Anna's lovely neck scratched before the other woman was booted from the club.

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