Britney Spears walks off X Factor

According to TMZ Britney Spears walked off the set of "X Factor" moments ago ... and according to several people in the audience, she was upset after a contestant butchered her song, "Hold It Against Me."

Britney did not come back immediately ... and four contestants auditioned in front of the remaining judges ... and an empty seat.

Someone connected with the show tells us Britney was not upset over the song -- and that she "Just took a short break.
Seriously?? It's called an audition for a reason Ms Spears..this is the stage where you weed off people who butcher your song and every other person's song, lol. You don't just walk off Ms Thang! Lol. You say ...NEXT and move on. Stop being a cry baby, lol.

Simon Cowell denied Britney's walk off the set but we know who to believe, lol.