Madonna: Acts of desperation

She may rule the pop world, but Madonna's acting career has been patchy at best. Now, as she makes her West End debut, Charlotte O'Sullivan says, 'Love the videos, Maddy... hate the movies'

One day, over the rainbow, Madonna will probably dominate the stage and screen. Sadly for her, Up for Grabs opens tonight. What's the bet she's so bad it hurts? I blame Sean Penn. For Madonna, as anyone who's seen 1985's Desperately Seeking Susan knows, used to be a fine actor. As the chunky scuzz-queen Susan – adored by Roberta, a young, bored New Jersey housewife – Maddy is looser than loose. She jiggles as she dries her armpits in a public bathroom, saunters away from one-night stands and picks through Roberta's diary with magnificent scorn ("It's got to be a cover: nobody's life could be this boring!"). Rosanna Arquette, who played Roberta, says she grew up wanting to be Natalie Wood. Madonna, you feel, grew up wanting to be Marlon Brando. A few months earlier, she'd been turned down by the producers of Footloose. The joke, it seemed, was on them.

And then Penn came along (he and Madonna met while working on David Rabe's off-Broadway play Goose and Tomtom). And something terrible happened – those jaunty limbs went stiff. Penn, a sometimes superb, sometimes indulgent actor, is a great believer in the Craft, and something of his preciousness, like herpes, must have rubbed off. In Shanghai Surprise, the film they made together after marrying in 1985, she was already holding herself differently. And talking as if she'd been stalking the voice-coaches all day. In Who's That Girl?, she played Nikki Finn – and the production notes prepared us for "a feisty, free-spirited femme destined to take her place amongst the screen's great comic heroines". Katharine Hepburn and Judy Holliday need not have worried. The script, admittedly, was duff; the real problem, though, was that Madonna had lost her knack for insouciance.

Next, she got herself cast in David Mamet's Speed the Plow on Broadway. The reviews (shock!) were lukewarm. And then it got really scary. Uli Edel's Body of Evidence cast Madonna as a woman so crazee that she poured champagne over her lover's body while holding a candle. She also had lines such as, "Ever seen animals make love, Frank? It's intense." Having learnt nothing from that experience (the only thing she objected to was that, at the end, her character was killed off – this, this alone, was "sabotage"), she went on to appear in Abel Ferrara's Dangerous Game, one of those pretentious where-does-life-end-and-the-movie-begin? dirges that tickle directors and no one else.

Madonna's comments about the film were revealing. She said that while the experience was "soul-destroying" and "violent", the performance itself was the best thing she'd done on screen. "At least I felt I was going somewhere, exploring new territory. I feel everything else I've done has been rather trivial." One chokes on the parlour-room grandeur of "rather", but the "trivial" is even worse. The very essence of Madge-the-icon is a blurring of such high/lowbrow distinctions. Madge-the-actress sounds not only masochistic, but horribly out of date.

Luckily, for those addicted to her savvy, sophisticated take on culture, we still had the pop videos. I'm fond of her pouty-sweet turns in "Papa Don't Preach" and "La Isla Bonita", but in 1989 her "promos" moved up a gear. "Like a Prayer" has Madonna as a gorgeous, defiant Mary Magdalene; in "Express Yourself", directed by David Fincher, she's a silken, bra-clad "boss"; in "Justify My Love", she staggers passionately around a Parisian hotel and kisses an androgynous girl. All of them are great mini-movies in which she's perfectly cast. What they make obvious, too, is Madonna's genuine, across-the-board love of cinema.

We all know about her interest in Gentlemen Prefer Blondes, but over the years she's also tipped cheeky winks at Fritz Lang's Metropolis, Jean Vigo's L'Atalante (she became obsessed with the actress Dita Parlo), Fellini's La Dolce Vita and Robert Aldrich's Whatever Happened to Baby Jane?. A bitchy Mark Wahlberg has pointed out that, these days, Madonna looks like something from Tim Burton's Beetlejuice. As it happens, Maddy's not frightened of ugliness or ageing in her videos. Any day now she probably will make one in which she wears a rat's-nest hairdo, causes mayhem, then tries to marry Winona Ryder.

Of course, for those who find the videos too short, there's also 1991's In Bed with Madonna, a documentary made by Alek Keshishian that allows our heroine to perform non-stop. Her bullish confidence isn't necessarily likeable, but it's marvellously 3D. A bonus is the sight of Warren Beatty (with whom she starred in yet another disappointing "movie movie", Dick Tracy) backstage. He's a bona fide movie star, but in front of this camera he appears merely vain and self-conscious – a rank amateur next to Madonna the pro.

And yet she can't stop trying to prove herself worthy in his world. One feared the worst with Evita – luckily, the film itself was so camp and strange that her gleaming, waxwork-dummy performance looked entirely at home. The wonder is that she won a Golden Globe. Evita didn't show that Madonna had remembered how to deliver lines. It showed that she could sing the words, "Screw the middle-classes!" with a straight face.

Things went from blank to worse with The Next Best Thing, possibly one of the most inept movies of 2000. It looks like crap, the story makes no sense and in the middle of it all is a tiny woman talking through clenched teeth. Madonna is famous for her steeliness, yet all you can smell here is fear. Naturally, she is not at her sexiest, though the script would have us believe otherwise (in show-and-tell style, the word "beautiful" crops up a lot). "As I descend further into this labyrinth called movie-making," a gloomy Madge once wrote in Vanity Fair, "I am stunned by the number of possibilities for feeling lonely and alienated." Jeez, lady, spare a thought for your fans. We're suffering, too.

Guy Ritchie's appearance on the scene is hardly cause for celebration. He's cast his wife in the lead of his new film, Love, Sex, Drugs and Money, which has apparently infuriated his partner, Matthew Vaughn, who wanted someone more bankable, such as Penelope Cruz. "It got a bit rough," a friend was quoted as saying. "Guy thought Matthew was doubting Madonna's acting-ability, but he was just being practical." Yeah, right. Of course he was doubting Madonna's acting-ability. On the evidence of her films, how could he not? A more important question, though, is what's so great about Ritchie? He can't direct anyone. And yet if the film flops, it'll be Madonna who takes all the flak.

As I say, the person who is really to blame is Sean Penn, who's still going around saying that Madonna is "untapped" as an actress. I think that, deep down, she believes him. Like Dorothy in The Wizard of Oz, she can't see the obvious: that she's been acting all along – that it's home from home. She thinks it's out there, and that the harder she tries, the closer she'll come to her goal. Maybe one day she'll realise her mistake. Until then – though it pains me to say it – I'd rather watch Toto tread the boards.