What she couldn't stop was the drama -- and many tears -- that followed between her and her girlfriends on the show. Whether they were staged or not, few who watch "The Hills" can doubt Conrad's deep emotions.

But the tumult made working with producers hired to shape her reality, well, awkward. Conrad called her relationship with DiVello "weird." After Montag showed up unannounced to the birthday party airing tonight, Conrad informed the producers she'd be taking a week off immediately as payback.

"He's a genius, and I have a lot of respect for the show he's created . . . but we've had a lot of arguments," she said. "They'd put us in situations we didn't want to be in. There were times I'd take my mike off and just stop."

Conrad said she started looking at the show solely as a vehicle to promote her business opportunities. In that regard, she's scored several notable successes -- a fashion label, a side career writing teen fiction, spokeswoman gigs, even the occasional guest starring role as herself.

"I can't act at all!" she said. "I'm so not interested."

For MTV, Conrad's exit leaves the network's top franchise in the lurch, and producers say they still haven't decided whether to continue the show without her. Montag and Pratt, ever willing to drum up drama as her adversaries, are pressing for more.

“I don’t know that we need her,” Montag told MTV News on Friday.

Audiences, quicker to find out news on "The Hills" in the tabloids than on the show, might also sense the story lines stretching thin. Though the series is still MTV's No. 1 show, ratings for the fourth season were down from the previous season's average of 3.9 million viewers to 2.9 million.

But that's of no concern to its ex-star now. Free of the pressure to emote weekly, Conrad said she's eager to lighten up. Her biggest post-show plans are drama-free.

"I'm excited to not have everything scheduled in advance," she said. "I can just call up a friend and grab lunch. I can wear white when I want to -- I could never do that on camera. I can go backless!"

"Yeah," she said, smiling. "I'm going to be real rebellious."

denise.martin@latimes.com