“Mean Girls” star Lindsay Lohan is spinning out of control, say her friends.

The teen superstar’s relentless work schedule, nonstop partying and multiple car crashes have taken a heavy toll on her emotions. She’s so stressed out that she’s showing up late to work on the set of her new Disney movie, is acting like a diva and is fighting with boyfriend Wilmer Valderrama, friends tell The ENQUIRER.

But her fast-lane lifestyle has also taken a toll on her physical health–landing her in Cedars-Sinai Medical Center with flu-like symptoms after running herself ragged.

“Lindsay’s headed for disaster,” said a close source. “With movie commitments through 2007, it’s all moving too fast for her to keep up.

“Her nasty attitude isn’t helping. And the crazier and more unpleasant her life gets, the more bitchy and overwrought she becomes.”

Friends weren’t surprised when Lohan got sick and was admitted to the hospital October 21.

“She was really asking for it,” said a friend. “She’s partying constantly and sleeping only a few hours a night.”

Just three days earlier, Lindsay smashed her BMW into a guardrail at 2 a.m. on her way to Wilmer’s house after a night out at the West Hollywood hot spot Guy’s.

“Fortunately, no one was injured,” said the close source, “but the car was so badly damaged, they had to call a tow truck.

“Wilmer was furious.

“The car accident was her third since she started driving–and it’s not surprising. Her car crashes are a metaphor for her life. It’s one wreck after another.”

The day after the accident, the 18-year-old star was supposed to be on the set of her new Disney movie “Herbie: Fully Loaded” at 5 a.m., but didn’t drag herself in until midday, said the friend.

“She’s in trouble with Disney execs,” the friend added. “Showing up late to the set, or not at all, has caused delays and infuriated the movie’s producers.

“On top of that, she complains about everything.”

Wilmer, 24, star of TV’s “That ’70s Show,” is getting fed up with her, too, said the close source. “He’s a nice guy, but I don’t think he’s going to tolerate it much longer.”

When contacted by The ENQUIRER, Lohan’s publicist, Leslie Sloane, stated that she can’t comment on Lohan’s health, except to say that “she’s under the weather.”

As for Lohan’s accident, it was Sloane’s understanding that she “blew a tire.”