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Jones says she has been constantly bad-mouthed by Rinna since the show wrapped (Celeb Apprentice began taping last fall; all episodes but the live finale have been shot). To back up the claim, Jones has gathered the series of tweets dating back months and a pile of emails from Rinna and turned them in to NBC's legal department, complaining she is being "harassed," according to a source familiar with the situation.

No comment yet from Rinna, who has since deleted the offending tweets, including some of Rinna posing with monster masks and featuring captions like "Great picture of me and Star Jones!!!! " (Although Rinna has removed them, many have been archived online.)

Saying that such attacks were "evidence of [Rinna's] instability," Jones also got lawyers from The Trump Organization and from Mark Burnett Productions involved in her fight this week to shut Rinna up.

"Star declined to make the cause of concern public as to not take away from her purpose of doing the show, which is charity," a rep for Jones tells E! News.

NBC declined comment. Calls to lawyers for Trump and Burnett were not immediately returned..

Meanwhile, a source familiar with the back-and-forth tells us that "Star is taking this very seriously."

"Lisa was so furious she was kicked off so early and blamed it all on Star. Lisa went home and started sending nasty emails. Star just collected it all and handed them over. It's in legal's hands now and they've warned Lisa to stop," the insider says.

"Star hasn't taken the behind the scenes fight public because she thinks it would ruin Lisa."

It's not the first time the Jones has had problems with her costars. She verbally attacked the ladies of The View, calling them "hateful" after she left the show.