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Usher won Hip-Hop Artist of the Year and Hip-Hop Song of the Year at the Radio Music Awards (search) Monday night. Linkin Park grabbed the Alternative Rock Song of the Year and Rock Artist of the Year.

This time Ashlee Simpson (search) sang for real. We think. The 19-year-old pop artist was among a slew of stars who played Monday during the program at the Aladdin hotel-casino on the Las Vegas Strip.

Destiny's Child (search) opened the celebrity-laden show, wowing a screaming audience with "Lose My Breath."

Train, Chingy, Elton John, Tim McGraw (search), Big & Rich, Gretchen Wilson and Alanis Morissette also dazzled the crowd with their performances.

But whether she liked it or not, Simpson was at the center of the show thanks to a glitch on "Saturday Night Live" last weekend that revealed she had been lip-synching one of her songs.

Before she sang "Autobiography" off her hit album, host Carson Daly (search) reassured Monday's audience they were getting a live performance.

"Live, yes live," he said.

When Simpson's band started playing, the younger sister of pop starlet Jessica Simpson screamed, "It's the wrong song." Seconds later, she told a stunned theater filled with hundreds of people that she was "only kidding."

Later in the evening, she told Daly in an off-stage interview that acid reflux disease had made her lose her voice four hours before her "SNL" appearances.

She didn't seem concerned about her slip up.

"You move on," Simpson said. "Things happen."

Politics also didn't spoil the night at the Aladdin, where rocker Linda Ronstadt was told to leave in July after praising "Fahrenheit 9/11," Michael Moore's unflattering documentary about President Bush.

Neither Moore nor Ronstadt appeared at the awards show but former pro wrestler Hulk Hogan made himself seen by wearing a T-shirt "Vote or Die!"

The two-hour show broadcast live on NBC. The nominees in each category were based on radio's top-playing songs. Radio program and music directors nationwide voted on the winners.

The Aladdin hotel-casino was recently purchased by an investment group led by Robert Earl, Planet Hollywood's founder and chairman.

The following is the list of Radio Music Awards winners:

Artist of the Year — Hip Hop/Rythmic Radio: Usher.

Artist of the Year — Top 40 Radio: Beyonce.

Artist of the Year — Country Radio: Tim McGraw.

Song of the Year — Rock Alternative Radio: Linkin Park — "Numb."

Song of the Year — Hip-Hop/Rythmic Radio: Usher — "Yeah!"

Artist of the Year — Rock Radio: Linkin' Park.

Artist of the Year — Modern Adult: Train.

Legend Award: Janet Jackson (news).

Cingular Artist of the Year: Usher.