They have a reputation for being raw and unpredictable. But is there any more to the Vines?

In a hotel room just off Trafalgar Square in London, Craig Nicholls is becoming visibly agitated.

Beneath a voluminous parka and a faded T-shirt featuring the Minutemen - the 1980s Marxist punk trio who once wrote a song called The Roar of the Masses Could Be Farts - the 26-year-old leader of the Vines is a mass of nervous tics. His left leg bounces up and down. He seems unsure whether to conduct the interview sitting on his bed, lying flat, or kneeling on the floor next to it as if he's praying. He seems equally unsure what to do with the Kentucky Fried Chicken that the Vines' manager recently bought at his behest - Nicholls famously exists on a diet of junk food. He picks it up. He puts it down. He stares at it through the tendrils of his fringe, as if expecting it to move of its own accord. He picks it up again.

All the time, he chatters nervously. "I have a reputation for being the maddest and craziest guy, but I'm the most quiet. It's the other three guys that raise hell. They're the crazy ones." He looks imploringly at bassist Patrick Matthews who is slumped in a designer chair across the room. "Tell him!" he insists. "Tell him! Tell him!" Matthews looks back at him with an unconcerned air. 

Even at the best of times, Nicholls is hardly a model of laid-back insouciance. At worst, he is famous for throwing tantrums that Naomi Campbell would consider slightly de trop. The last time the Guardian interviewed him, he destroyed a dressing room because a security guard had the audacity to knock on the door and ask if he was smoking pot (he was). He once smashed up a television studio where the Vines were rehearsing because he was hungry.

There's a pause. "Yeah," Matthews drawls laconically, "we're the crazy ones."

The Vines' craziness or otherwise is a familiar topic. Not even their vast success in the US, where their 2002 debut album Highly Evolved shifted 1.5m copies, has done anything to dissuade the public from their popularly held belief that Craig Nicholls is barking mad. Indeed, mental health issues appear to have underpinned their story ever since they emerged from Sydney at the end of 2001, proffering a combination of Nirvana-inspired noisy alt-rock, woozy, vaguely psychedelic acoustic songs, angsty lyrics and unpredictable live performances that frequently ended in a mass of smashed equipment.

At a time when rock music was in a post-Britpop slump, the Vines seemed thrillingly raw and unpredictable. Nicholls and Matthews, 28, had met in their teens while working in McDonald's. Nicholls claims that during the recording of their debut album, he was so naive that he didn't realise bands had to go on tour.

The Vines began attracting hysterical critical plaudits: never knowingly underwhelmed, the NME claimed that Highly Evolved was "the greatest debut album ever made". But immediately trouble began to brew. It emerged that their drummer, a diagnosed manic depressive called Dave Olliffe, had suffered a nervous breakdown during the recording of the album in LA and had been replaced by Hamish Rosser.

Olliffe then took to the band's website, denouncing Highly Evolved's producer Rob Schnapf as "the biggest cunt there is" and claiming that he was about to rejoin the band. Olliffe later retracted his comments, but the incident set the tone for the next two years. Every critical or commercial victory was somehow undermined. The band appeared to be in a perpetual state of disarray.

When Highly Evolved entered the American chart at number 11 - a situation certainly not hindered by their US label's decision to sell the CD at a discount - Nicholls celebrated by calling their US label boss "that cunt" and having him thrown off the band's tour bus. The critical hosannas were somewhat tempered by the news that Nicholls had smashed one journalist's Dictaphone in a fit of pique and excused himself from another interview by locking himself in a toilet for two hours. Invited to perform on Jay Leno's Tonight Show, Nicholls threw a tantrum in rehearsal, smashing up equipment and throwing a light at Rosser.

The band were ejected from the studio, their appearance on the programme cancelled. "What do I get mad about?" says Nicholls. "Like, if I'm wearing jeans and Patrick is wearing jeans, it's like fuck you! I'm wearing jeans today! And we have fights with Hamish because he wears T-shirts with four-letter words on them and we don't think that's appropriate. Also," he says, warming to his theme, "he's taken a lot of acid and he's always talking about it. Hamish is the weirdest, but it's not his fault. He's done something to his brain and he can't get back." He laughs uproariously.

"Great drummer, though." What effect have the tantrums and fighting had on their relationship with their record company? "Some of their people are a bit tense around us now," admits Matthews, sheepishly. "I think they're pretty tense to start off with, maybe." "We almost give them a heart attack," chuckles Nicholls.

You can see the record company's point. By the end of 2002, when the band's US tour was pulled after Nicholls and bassist Matthews began trading punches onstage in Boston, stories of Nicholls's erratic behaviour had completely overshadowed the Vines's music. Critical opinion on the band seemed to shift. Reviews of live shows featuring Nicholls howling tunelessly into the microphone, falling off stage and smashing his guitar ceased being awestruck descriptions of a tortured genius at work and began openly wondering what the point was. "Witless, dismal, joyless, depressing," complained one Guardian critic of a performance last year at the Astoria.

According to Matthews, he wasn't the only one: "Do you remember that guy in Amsterdam? " he asks Nicholls. "He said the first half of our concert was the worst thing he had ever seen in his life." Nicholls laughs, before becoming slightly huffy and sarcastic: "It's like, I'm sorry, I wasn't aware that I was supposed to be getting onstage and impressing anybody," he sniffs.

It's a deeply peculiar thing to say - if you're the lead singer in a rock band, getting onstage and impressing people rather seems to be the point - but then, there is no getting around the fact that Nicholls is a deeply peculiar man. The songs he has written for their new album, Winning Days, have met with mixed reviews, despite sticking to the same formula that grasping for the smelling salts when Highly Evolved was released.

Perhaps mindful of the vagaries of the press, he seems to be making an effort today. My Dictaphone remains in one piece and Nicholls stays put throughout, which given his past form, virtually counts as a charm offensive. In addition, he has allegedly given up his prodigious marijuana habit, which some felt was the cause of his erratic behaviour.

However, even drug-free and on his best behaviour, there would be little chance of mistaking him for normal. He cannot decide whether to brazen out the stories about his behaviour - as he points out, his favourite band, the Kinks, used to fight onstage "and that's kind of what attracted me to being in a band, that there were no rules, that you could do things how you saw them" - or to try and convince you that tales of his instability and violence are greatly exaggerated. "People get surprised when they meet me," he sighs. "They expect me to throw something at them. Some journalists twist your words a little." There is always the chance that they simply misheard him.

Perhaps as further evidence of the alienation that led him to write a song called Fuck the World, Nicholls appears to have invented his own accent. It originates somewhere in the Antipodes, but certain vowels seem to have slipped their moorings and ended up in the middle of the wrong words.

Discussing the songs on the new album, he claims that "hoff of thim arralld" (which means that half of them are old). He is also big on something called loff, which turns out to be the opposite of hate.

Once you have navigated the dialectal minefield, there are other matters to contend with. Nicholls' conversation has a tendency to go wildly off-piste, slaloming between topics without warning, before abruptly ending with a firm, satisfied "yeah". On any occasion where his answers stray dangerously close to making sense, he rectifies the situation by throwing in a multitude of pauses, affirmations and apparently random statements. He occasionally winds up sounding rather hurt and defensive about subjects he has brought up himself.

Ask him about whether he thinks some of the Vines's problems stemmed from the punishing tour schedule that comes with trying to break America, and you get this in response: "In America, there was a lot of people saying that they thought we were going to self destruct, so, yeah, like, we definitely didn't want that. We wanted to be productive as a band. That was our goal: making albums, writing songs, listening to CDs and not, like, whatever, the 80s rock or whatever. We're not those kind of people. We're not trying to make any kind of judgements on anyone. We've got no messages. We just want to make good albums. Yeah."

While you're pondering what 1980s rock has to do with the band's punishing tour schedule, or indeed where the topic of the Vines having a message fits in, you also start to wonder how much of this is for real, and how much of it is a defence mechanism, a rather long-winded method of telling you to mind your own business.

Throughout it all, Matthews never attempts to clarify or correct anything his bandmate says. Although he is apparently flummoxed by the simplest of inquiries, Nicholls occasionally reveals a sharp humour and self-awareness: "I always say to the other guys, if you want to throw a TV out of a hotel room window, then do it just before you leave the hotel, because there might be something you want to watch." 

In addition, he frequently appears to be sidestepping awkward questions by the simple expedient of behaving as if you have asked something completely different. He replies to an inquiry about how American audiences - who are famously unstinting in their desire for professionalism onstage - have received some of The Vines more outré performances with a lengthy anecdote about how much he likes 1990s alt-rock band Pavement.

He claims that Rob Schnapf, has been attempting to school him in interview technique, although it is unclear precisely what Schnapf has told him, which tends to suggest his schooling has failed: "He's given me advice about interviews. I'd be sitting there, saying 'Oh! I can't explain it, I can't explain it! I've opened this can of worms and now there's all worms hanging out and it looks really ugly!' And he's just saying, yeah, you know? He's played in bands before. We can relate to him on that level. He has great depth to him."

He suddenly sounds angry. "You see the thing is, actually, I'm not a fucking lunatic. People say to me, you know, maybe I could cancel our next tour and check myself into an insane asylum. I'm not necessarily proud of it, but I'm not ashamed of it either, because we make songs. As a band that's how it works, you put yourself out there, sharing yourself and your music with people. You hope they might connect with it. They might come up to you and say "hey man, I like your album"! And then maybe other ones go "yeah." 

He gives up on that train of thought, and unexpectedly returns to a much earlier one, about which he seems to have changed his mind. "I'm not trying to say that I'm really quiet and all the other guys are loud," he concludes.

"We're all as messed up as each other. Yeah." His leg still bouncing up and down, he goes back to staring out his chickenburger.