The MISS INDEPENDENT singer, 23, and American Idol runner-up Justin Guarini, co-starred in the film musical, which entered the US box office charts at a lowly number 11 in 2003.
Three years on, Clarkson is still embarrassed with the movie.
She says, "Two words: Contractually obligated.
"I knew when I read the script it was going to be real, real bad, but when I won, I signed that piece of paper, and I could not get out of it.
"Seriously, I never thought I could act, but I knew I could sing. Not to sound cocky, but I can."