In her recent Monterrey, Mexico concert Hilary had some technical problems which caused her microphone to not work for a few seconds in the beginning of her song "Play With Fire." The technical glitch was caught on video, which caused Perez Hilton to claim that Hilary was lip-syncing the song.
Today in a People.com article, Hilary's reps denied that she was lip-syncing.
"She was not lip-synching," her reps tell PEOPLE. "It was faulty equipment. There was no sound coming out, but she was singing."
Having seen her in concert a number of times, it is my opinion that Hilary probably uses some type of sound enhancement during her shows, but it sounds like she is singing live most of the time. This video on the other hand proves nothing, and it's really a non-story.