"Ella Enchanted" is the most heartbreaking type of movie disappointments.

What could have been wonderful has been processed into cute but throwaway fluff. It lingers like a half-cast spell, its potential as obvious as every opportunity director Tommy O'Haver and a squad of screenwriters missed.

Lacking faith in the material that made Gail Carson Levine's novel special, the filmmakers puree "Ella Enchanted" into a second helping of "Shrek" with a slice of "A Knight's Tale" on the side.

Anne Hathaway, who exuded fairy tale charm in "The Princess Diaries," plays Ella of Frell, a lass cursed to do whatever she is told. When she was born, Ella received this "gift" of obedience from Lucinda, a boozy fairy godmother (Vivica Fox).

Ella takes every command literally. When someone says, "Hold your tongue," she sticks her fingers in her mouth and grabs her tongue. When someone shouts, "Freeze" she comes to a stop – even in mid-air.

Ella lands in the same predicament as her partial namesake, Cinderella. After her mother dies, Ella's father marries a cruel, ugly woman with two cruel, ugly daughters. Dad is seldom home, leaving Ella alone with her evil step-mother and step-sisters.

"Ella Enchanted" mixes modern culture and fairy tales much as "Shrek" did. Many of the pop references are already a half-decade out of date, though. To wit: "If the gauntlet doesn't fit, you must acquit."

Like most girls in the kingdom, Ella's stepsisters are crazy for Prince Char (Hugh Dancy), the frequent Medieval Teen cover boy. Ella isn't mad about the prince, though. She is a political activist who opposes Char's ruling uncle, Sir Edgar (Cary Elwes, who played the hero in "The Princess Bride.")

Political allegory piles up awfully thick for a children's movie. Sir Edgar, whose chief adviser is a computer-animated snake named Heston, has indentured the elves, expelled the ogres and enslaved the giants (how Sir Edgar humbled a colony of giants is a mystery, because all they had to do was step on him).

As Prince Char's coronation approaches, Ella expects he will govern as ruthlessly as his uncle. Once she meets the prince, though, Ella realizes Sir Edgar has not corrupted him.

Ella encounters the prince on her journey to a giant's wedding, where she hopes to find Lucinda and convince her to lift the spell of obedience. With a talking book (Jimi Mistry) to guide her, Ella also is joined by Slannen (Aidan McArdle), an elf who wants to be a lawyer (I was expecting him to say dentist).

Like "A Knight's Tale," "Ella Enchanted" includes musical numbers set to classic rock songs. This gimmick works at the wedding when a giant says, "Sing us a song," obliging Ella to belt out Queen's "Somebody to Love." The joke would have been funnier if this were a single burst of '70s music and not part of a marketable soundtrack. The finale, where the cast joins to sing Elton John and Kiki Dee's "Don't Go Breaking My Heart," is much less successful.

Hathaway is a delight, and no matter how much they filtered her voice, she does a dynamite job with "Somebody to Love." Dancy also gets it right; he is the only cast member who doesn't act as if he were in the middle of a big joke.

Minnie Driver appears as Ella's nursemaid, Mandy, a house fairy who offers no more help than the occasional pep talk. Any function that Mandy serves in the story was lost in the editing room.

Much of "Ella Enchanted" is enjoyable, but this fractured fairy tale easily could have been something to treasure if it were allowed to be its own movie. Unfortunately, director O'Haver was under Hollywood's spell of obedience – obedience to formula. Magic doesn't work that way.