Celebrity News:

Not Celebrity Relapse? Singer Jessica Sierra, who was one of the finalists on American Idol the year that Carrie Underwood won, is among the participants in Celebrity Rehab, a VH1 show depicting various semi-stars undergoing detox and treatment.

But the treatment on the series, which premieres Jan. 10, apparently did not take for Sierra. The Associated Press says she was jailed early Saturday morning ''after a drunken confrontation with police and onlookers'' in Florida. That arrest comes less than two weeks after she pleaded no contest to charges of battery and possession of cocaine.

Her appearance on Celebrity Rehab was reportedly taped in July. A VH1 release said one of the show's participants did not complete its 21-day program, but it did not specify which. Others on the show include Jeff Conaway, Brigitte Nielsen, Daniel Baldwin and Cleveland-born porn star Mary Carey.

Rock Hall Walks Hard. Actor John C. Reilly will give a musical performance at the Rock and Roll Hall of Fame on Wednesday to help promote his new movie, Walk Hard: The Dewey Cox Story.

Reilly plays singer Cox in the very amusing parody of music-star biographies like Walk the Line. He will walk the red carpet about 9:30 p.m. Wednesday and give an hourlong show at 10 p.m.

It's a ticket-only event. You can register for a chance at tickets by e-mailing coxroxcleveland@yahoo.com. There are also sundry radio-station giveaways in progress.

The movie, which opens Dec. 21, comes from producer-funnyman Judd Apatow (Knocked Up, Superbad), recently dubbed the smartest person in Hollywood by Entertainment Weekly.

Reilly's credits include Chicago, Year of the Dog, Talladega Nights, A Prairie Home Companion, Magnolia and Boogie Nights.

Montel Apologizes. TV host Montel Williams has expressed regret for threatening a reporter in an appearance in Savannah, Ga.

The Savannah Morning News says Williams, displeased with his treatment at a news conference, later saw reporters working on an unrelated assignment. He approached them and said, ''Do you know who I am? I'm a big star, and I can look you up, find where you live and blow you up.''

''I'm not sure if he meant 'blow me up' and ruin my career or really blow us up,'' said one reporter. ''But it was threatening.''

In a statement to the newspaper, Williams later said, ''I mistakenly thought the reporter and photographer in question were at the hotel to confront me about some earlier comments. I was wrong and apologize for my overreaction.''