In late 1999, Spears appeared on the sitcom Sabrina, the Teenage Witch and performed the song "(You Drive Me) Crazy"; this cameo was a cross-promotion for the film Drive Me Crazy, which starred Sabrina's Melissa Joan Hart and was named after the song.^[38]

June 2002 saw the opening of Spears's restaurant, Nyla, in New York City, which served Louisianan and Italian cuisine. However, she was pulled out of the business venture in britney spears controversial nude pictures November as a result of debts and management issues. Nyla officially closed in 2003.^[20] In the same year, Limp Bizkit frontman Fred Durst confirmed that he was in a relationship with Spears. Durst was also hired to help write and produce tracks for her album In the Zone, which were eventually scrapped.^[60]

On the evening of January 3, 2008, after not sleeping for over four days police were called to Spears's home after she refused to relinquish custody of her children to Federline's representatives.^{NUDE BRITINY SPEARS SEXY PHOTO id="cite_ref-136" class="reference">[137]} She was hospitalized at Cedars-Sinai Medical Center after she "appeared to be under the influence of an unknown substance",^[138] though blood tests tested negative for any illicit substances.^[139] She was held for psychiatric evaluation for two days.^{[140][141][142]} Pending a February 19 hearing, Commissioner Scott Gordon issued an order on January 14 stating that her visitation rights have been suspended indefinitely. On January 31, a court placed Spears under temporary co-conservatorship of her father James Spears and attorney Andrew Wallete, giving them complete control of her assets.^[143] As a result of an order placed by her psychiatrist, she was taken to UCLA Medical Center to be put on a 5150 involuntary psychiatric hold for the second time that month.^[144] On February 1, a restraining order was issued against Sam Lutfi, a prominent figure in Spears's life.^[145][146] She was released from the hospital on February 6, amid speculation that she has bipolar disorder,^[147][148] although medical records are classified, and no confirmation has been made. Her parents expressed disappointment and concern at the decision to release her.^[149] She has regained some visitation rights after coming to an agreement with Federline and his counsel.^[150] On July 18, 2008, Spears and ex-husband Federline reached a custody settlement in which Federline retains sole custody while Spears keeps her visitation rights.^[151]

Spears had her first starring role in the 2002 film Crossroads,^[61] in which she portrayed a high school graduate who travels to find britney spears controversial nude pictures her long-lost mother. The movie was poorly received,^[62] as was Spears's performance; Spears received Razzie Awards for Worst Actress and for Worst Original Song.^[63] Nonetheless, the film grossed over $60 million worldwide.^[64] Spears also made cameo appearances in Austin Powers in Goldmember and Longshot.^[65] Footage of Spears appeared in the 2004 documentary Fahrenheit 9/11, which samples a 2003 CNN interview about the Iraq War in which Spears says, "Honestly, I think we should just trust our president in every decision he makes and should just support that, you know, and be faithful in what happens."^[66][67] Spears made her third consecutive MTV Video Music Awards performance. While performing "I'm a Slave 4 U", she controversially utilized caged animals and danced erotically with a large albino python draped over her shoulders. Animal-rights organization PETA claimed that the animals featured in the performance were mistreated and cancelled plans for an anti-fur billboard that was to feature Spears.^[68] Her career success was highlighted by Forbes magazine in 2002 as Spears was ranked the world's most powerful celebrity.^[69] At a performance at the 2003 MTV Video Music Awards, she appeared with Aguilera performing the song "Like a Virgin", and was later joined by American pop singer Madonna. Spears locked lips with Madonna in a highly-publicized kiss.^[70][71][72]

Spears is ranked as the eighth best-selling female recording artist in the United States according to the Recording Industry Association of America with 31 million certified albums and one of the world's britney spears nude wallpapers best-selling music artists having sold an estimated 83 million records worldwide.^[8][9]

Spears married childhood friend Jason Allen Alexander on January 3, 2004, at The Little White Wedding Chapel in Las Vegas.^[76] The marriage britney spears sex picture lasted 55 hours, ending with an annulment stating that Spears "lacked understanding of her actions to the extent that she was incapable of agreeing to marriage because before entering into the marriage the Plaintiff and Defendant did not know each others' likes and dislikes, each others' desires to have or not have children, and each other's desires as to State of residency."^[77][78]

Spears released her third studio album Britney in November 2001. Although not as successful as her previous albums,^[1] she assumed some creative britnei spirs sex control by co-writing five of the album's tracks.^[49] It surpassed Michael Jackson's album Invincible when it had a successful debut at number one in the U.S. by selling 745,744 units during its first week.^[50] The album's success made her the only female artist in music history to have her first three albums debut at number one.^[51][52] The album fared well with critics such as Allmusic who gave it 4.5 out of 5 stars, describing the album's title tracks as being "pivotal moments on Britney Spears's third album, the record where she strives to deepen her persona, making it more adult while still recognizably Britney."^[53] In contrast, Rolling Stone said of the album Britney "belabors the obvious: Spears is one month away from entering her twenties and clearly needs to grow up if she's going to bring her fans along."^[49]