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The future of America's number one comedy, "Two and a Half Men," remains unknown following the news that its star, Charlie Sheen, checked into a rehab facility this week "as a preventative measure" in the wake of his Aspen arrest on Christmas Day.

"He will take some time off his series," Sheen's rep confirmed to Pop Tarts. "He has asked that his privacy be honored.  No further statements are planned."

According to Variety, the hit CBS series is in production this week on the 19th episode of its 23-episode season, which puts a murky spin on whether the season will actually be completed and go to air as scheduled -- potentially costing the network hundreds of thousands of dollars in lot production time and negative publicity.

SLIDESHOW: Click here for photos of Charlie Sheen

"The announcement that Charlie Sheen is going into rehab and leaving the show is a top blow for CBS.  It is also not good news for his future ability to obtain insurance coverage, which could affect his employability in the long-term," media expert Michael Levine of Levine Communications said. "I assume the late night hosts will have a field day with this latest Charlie Sheen disaster."

This isn't the first time Sheen has checked into rehab. In 1990 the actor reportedly checked into a drug and alcohol facility suffering "extreme exhaustion due to his arduous filming schedule" and in 1998 he was hospitalized after "consuming excessive amounts of drugs and alcohol."

"Insurance companies always look for any kind of risk associated. For example someone like Lindsay Lohan, who has a built-in track record and is risky to a production, would most likely have a very high insurance premium or be uninsurable," said entertainment attorney Michael G. Dave of the Los Angeles law firm Marcus, Watanabe, Snyder & Dave. (Dave does not represent Lohan or the CBS program.) "Premiums could be raised [when Sheen returns to the set], but it will depend on how much loss is associated with him going to rehab and his track record."

And the controversy surrounding Sheen's arrest and being formally charged on suspicion of felony menacing, misdemeanor third-degree assault and misdemeanor criminal mischief may very well be grounds to release Sheen from his contract over violation of a moral turpitude clause.

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"Actors on shows have specific conduct clauses and CBS will have to look at the negative fallout versus taking a guy off a very successful show," criminal defense and entertainment attorney Steve Cron told us. "It isn't a morals game; it is a question of what is going to cost them more money."

However, according to a CBS insider, the cast and crew are not stressed but are "surprised" by the news and expect Sheen to be absent for only a brief amount of time.

"Chances are he will be allowed to go back to work very soon," added another insider. "Working will probably be an important part of his recovery and sobriety."

And the network executives and show producers are certainly sticking by their leading man.

"CBS, Warner Bros. Television and Chuck Lorre support Charlie Sheen in his decision today to begin voluntary in-patient care at a treatment center," said the joint statement. "We wish him nothing but the best as he deals with this personal matter. Production on 'Two and a Half Men' will be temporarily suspended."

However Sheen isn't alone in leaving a show amid filming, and the outcome hasn't been particularly positive.

Long-time television personality Pat O'Brien "parted ways" with "The Insider" in 2008 just a few months after his second stint in rehab, and was replaced on the show by his stand-in, Lara Spencer. In 1980 Mackenzie Phillips' character in "One Day at a Time" was "sent out of town" as Phillips was let go from the sitcom over allegations of drug abuse. The starlet returned to the series the following year but was fired for good in 1983 after refusing a drug test.

Mischa Barton also sought professional help just as her axed show, "The Beautiful Life," was about to start shooting and production was delayed a week, but the producers claimed it was because sets were not ready.