What's eating Robbie Williams?

What, exactly, is the matter with Robbie Williams? Why isn't he enjoying it all? After all, he's 33 and single, the idol of millions, stupefyingly rich, desired by all manner of pretty people of all known genders, the owner of a comfortable home in Los Angeles and the performer and co-writer of a solid catalogue of hits at least one of which, "Angels", is on the playlist for any number of weddings and funerals. So where did it all go wrong?

Robbie Williams last week checked into a rehab clinic in Arizona to rid himself of a severe dependency on anti-depressants which, according to some accounts, he washes down with as many as 36 double espressos and copious draughts of Red Bull - a caffeine intake sufficient to unnerve Keith Richards himself.

In the same week, EMI, the record company which signed him only five years ago for a reported [pound]80m advance, predicted a 15 per cent drop in profits and warned darkly of possible job cuts. They cite poor performance in the American market, which has proved less than susceptible to Williams's legendary charm.

No one specifically cited the company's investment in his disappointing US venture as a contributory factor, but the industry has major form when it comes to throwing enormous sums at artists just as their careers peak, and then commence the downward slide. The words "Mariah Carey" and "Michael Jackson" still echo in the nightmares of troubled Sony stockholders.

To add insult to injury, a reunion tour by the other four members of Take That, the boy band that launched his career, has proved far more successful than anybody could possibly have predicted.

Their comeback hit, "Patience", scooped Best Single at last week's Brit awards: after collecting their gong, they didn't even mention Williams. Meanwhile Amy Winehouse, celebrating her win as Best British female, growled her hit lyric, "They tried to make me go to rehab/I said no, no, no."

Williams has taken home more Brit awards in his time than any other artist, both as a member of Take That and as a soloist, but he wasn't even in the running this year. His latest album, Rudebox, was greeted with derisive reviews and derisory sales. Falling out with his long-term collaborator and co-writer Guy Chambers certainly didn't help.

Williams's ongoing relationship with Take That, the group he joined when he was 16, has been almost an archetypal rock and rollercoast-er ride. He responded to his 1995 ousting by seeking out an instant credibility injection in the form of extensive semi- public boozing and coke-snorting in the company of Oasis, fellow Mancs and front-runners in the Bad Boy stakes. They soon fell out: Noel Gallagher famously dismissed him as "that fat dancer from Take That".

The Gallaghers certainly bear grudges: picking up their own Brit award, Noel of that ilk described Williams's music as "dog shit," while Liam, whose wife, Nicole Appleton, is a former girlfriend of Williams, was slightly more eloquent, according to The Sun, which once again wore out its corporate asterisk key.

"What's his f***in' problem, man? "We all know what it is - he's a f ***in' drama f ***in' queen. If you've got a f ***in' problem, why do you want the whole world knowing about it? He has to be on the front f ***in' pages, doesn't he? Just sort your f ***in' self out. You make a f***in' crap album then want everyone to feel f***in' sorry for you. "F***in' tosser!"

Williams has been troubled for quite some time: his first spell in rehab, brought on by cocaine and alcohol problems, came hard on the heels of his ejection from Take That. He could console himself, though, with the knowledge that, as his personal stock soared - he has sold more records than any other British solo artist - the careers of his former bandmates foundered.

Neither Gary Barlow, considered "the talented one" because he took the bulk of the lead vocals and dabbled in songwriting, nor Mark Owen, "the pretty one" whose most notable post-Take That achievement was to win Celebrity Big Brother, made any noticeable mark on the wider world after the disintegration of the band. It is only now, more than a decade later, that his former colleagues have come anywhere near to the spotlight.

But clearly wealth, fame, public adoration and a heaped side dish of Schadenfreude are not enough to provide a counterweight to world- class depression.

He has spoken frequently - and, unless you happen to be Liam Gallagher, not unmovingly - of his insecurities, of his fear of relationships, of his terror at the thought of parenthood and passing on his inner torment to children, of the "open wound" which, to him, is his life.

Just last year, the Asian leg of a world tour had to be cancelled due to the star's "stress and exhaustion".

The only time I was ever in the same room with him, at the first night of a revival of The Rocky Horror Show, he was suffering from an acute panic attack in the crowded bar and receiving urgent counselling from a person or persons unknown over his mobile phone.