America's Sweetheart orders herself a no-nonsense cup of coffee, a sober brew to match her new outlook.

Decaf. Black. No sugar."I've just about had it with sweetness," Sandra Bullock says with a wink as a studio employee scuttles away to fill her order.

It's hard to blame Bullock for flirtation with bitterness as she prepares to return to the same Hollywood limelight that cheered her arrival four years ago, then spat her out.

"I can't believe I'm still standing," says Bullock, 33, still managing a smile. "You learn and you learn painfully. My life was a sinking ship."

That ship, of course, has a name: the Seabourn Legend, a massive luxury superliner bound for the Caribbean in "Speed 2: Cruise Control" which veered dangerously off-course, almost shipwrecking Bullock's promising film career.

Bullock badly needed a runaway success, yet the beautiful star with the liquid brown eyes could only watch like a helpless passenger as the $120 million production spun out of control.

"I didn't know that I was allowed to say, `We need to make it better,' " she says. "I didn't realize the backlash."

The ship capsized at the box office like some sort of exclamation point, punctuating her list of three back-to-back, high-profile clunkers.

"I laugh at it," she says now. "Actually, it was a blessing. When it happened, this weight lifted. The things that success brought were the boulders for me: the accolades, and gifts and stuff that I didn't earn."

The movie-going public quickly grew impatient with its Girl Next Door, eager to digest the bevy of fresh babes. There were Gwyneth, Ashley and Minnie, after all.

"There's always going to be a new woman, always going to be a new guy. It's out with the old and in with the new," Bullock says. "The interesting thing, too, is that this is the only industry that's willing to welcome someone back in."

Bullock makes her comeback this summer in "Hope Floats," in which she plays Birdee Calvert, a former cheerleader and prom queen whose picture-perfect life collapses in very public humiliation and betrayal, prompting a harrowing bout of self-examination and streaked mascara.

Sound familiar?

"It was painfully the right time. So many odd things were happening in my life, where I was, like, `I can't believe this is happening right now. I just want to kill myself!' Then I was like, `You know what? It's exactly what seems to be happening to Birdee in this film. So use it.' "

Lynda Obst, producer of "Hope Floats," says Bullock was at a crossroads: "I think it was a time in Sandy's life - after `Speed 2' and the kinds of pleasing roles she was doing - where she felt she could no longer just show that one side. She had to strip down, she had to show her subtlety and her depth. She needed to be unpleasing."

Bullock knew she had to turn her cute ship around - she had been the very model of a pleasing star since arriving in 1994 for her turn aboard the Great Hollywood Ingenue Ride.

Appropriately, she slipped into the driver's seat of a Santa Monica city bus as the adorable Annie in "Speed," gripping tightly to the wheel of her own streaking career.

Two other hits put her on the express lane: the tender "While You Were Sleeping" and "The Net," a Web-based thriller. The actress who was voted in high school "Most Likely to Brighten Your Day" had stumbled upon a winning franchise: She became the star for whom we all rooted.

Without missing a beat, she signed up for three more films: the comedy "Two If by Sea," the "Speed" sequel and the World War I drama "In Love and War" - each critical and commercial failures.

That, she says, is when "the roof caved in."

It was Bullock's gnawing need to keep moving - to never turn down work, to never stop the ride - that she blames for her career missteps. She feared the public's love affair with her could end at any time unless she kept going. It did anyway.

"That was my mistake. I didn't breathe. I didn't do what was going to make my work better - which was live life a little, let it sink in," she says.

"I don't ever again in my life want to be in such a blur because of fear. I didn't pay attention or really experience where I was. That, in the past year, has changed 100 percent."

Fleeing the dog-eat-puppy life of Los Angeles, Bullock retreated to Austin, Texas, where she started a production company, Fortis Films, and began to build her real-life dream house. She also cleaned house, firing her agent and lawyer.

Vowing never again to be timid on an out-of-control project, Bullock nursed "Hope Floats" for two years as an executive producer, supervising everything from the sets to the soundtrack.

"I'm a bull in a china shop. That's my energy. I am out there," she says.

Bullock is currently finishing up work on her next outing, "Practical Magic," opposite Nicole Kidman. Next month, she begins work with Ben Affleck on "Forces of Nature." And down the road are more than a half dozen scripts.

"People say, `Oh you're back.' Well, I didn't really go anywhere. I just did a couple of stinkers. That was my learning process. I went to school for a few years. `Speed' was an unexpected success and I saw myself trying to appeal to everybody, to fit in."

Now Bullock looks back on even the stinkers with gratitude. They brought her, she says, to the place she is now: Wiser, more aware, less likely to board the next ridiculous cinematic contraption.

"I'll never get too big for my britches because I know what size I wear."