Attempting to perform "Autobiography," her second song of the night, Simpson found herself singing along to the music and lead vocals of her first song "Pieces of Me."
She held the microphone at her side as her canned voice boomed across the studio, danced an awkward jig and then ran off the stage as the vocal recording was shut off and NBC cut away to a commercial.
At the end of the show, "SNL" host of the night Jude Law quipped, "What can I say? Live TV." Simpson, standing next to him, blamed the mishap on her musicians. "My band started playing the wrong song," she said. "I didn't know what to do so I thought I'd do a hoedown."
A statement issued by Geffen Records, Simpson's label, claimed there was "a computer glitch," while a representative for the show said that the song that came up was a backing track.
The following Monday, Simpson called into MTV's "Total Request Live" and explained that because of complications arising from "severe" acid reflux she had lost her voice and that her doctor had advised her not to sing.
But the incident tarnished Simpson's rep for months. In January 2005, Simpson performed "La La" during the halftime show for the Orange Bowl in Miami and got boos from the crowd of more than 70,000 spectators.
Simpson attempted to build credibility in '05 with a U.S.-Canada tour that she described to reporters as "stripped down," without effects like pyrotechnics, just "me and my band getting out there and having fun."