Ashlee Simpson [ tickets ] slinked off the "Saturday Night Live" stage in mid-performance this weekend (10/23) after a pre-recorded vocal track for a song she had already performed earlier in the show sprang from the speakers.

Simpson's first song, her hit "Pieces of Me," went off without a hitch. But when she took the stage again, this time to perform "Autobiography," "Pieces of Me"--complete with Simpson's pre-recorded voice--began playing again. After some awkward dance moves, Simpson walked off stage.

At the end of the show, Simpson apologized and deflected the blame. "I feel so bad," she said. "My band started playing the wrong song and I didn't know what to do, so I thought I'd do a hoe-down. I'm sorry!"

In a Monday (10/25) interview on New York City radio station Z100 FM, Joe Simpson, Ashlee's father and manager, said that he convinced Ashlee to use backing tracks when acid reflux caused her vocal cords to swell.

"[Ashlee] sang in the rehearsal--there's a full rehearsal right before the show, which is with a live audience--and by the end of that time she was so scratchy and her throat was hurting her so bad she started crying," Joe Simpson said. "We called ... her doctor in L.A.; he said, 'Don't let her sing.' I said, 'There's no way I can not let her sing--we've got to sing the show.'

"So we made the decision to pull up backing tracks to help her push through the song, because otherwise she would've sounded just like a frog--and no one wants to hear a frog on 'Saturday Night Live' unless it's a skit."

Simpson said that backing tracks were also to be used for "Autobiography," the aborted second song, because additional instrumentation was needed to fill out the four instruments in Ashlee's band.

"So you use a backing track there, which is the other instruments, and it's all on computer," he said. "Our young drummer was so excited to be on "Saturday Night Live" [that] he did not reset the machine after he did "Pieces" for the next song. So he went back in, pushed the button, and was still playing the song that he started the show with."

The drummer couldn't hear the track through his ear monitor, "so he just was happy in the world playing the wrong song," Simpson said. "The other players, we told them that if anything ever goes wrong, you play through the music. But Ashlee obviously couldn't sing the same song because it would look pretty asinine.

"So she gave you a Texas shuffle, gave you a little dance, freaked out, didn't know what else to do because no one ever went to commercial, so she finally just walked off the stage."

Simpson claimed that everyone "from Celine [Dion] on down" relies on backing tracks from time to time.

"If the worst you can find [on Ashlee] is that she got sick and had to use a backing track to help her, well, God bless her."