FACTBOX-Personal meltdown of Britney Spears

LOS ANGELES (Reuters) - Troubled pop singer Britney Spears was hospitalized on Friday after a standoff at her house over the handover of her two sons following a court-monitored custody visit.

Following are some major episodes in the personal meltdown of the former teen pop phenomenon, now 26, who in 2002 was ranked the most powerful celebrity in the world by Forbes magazine.

* Filed for divorce from Kevin Federline after two years of marriage and two months after the birth of their second child (November 2006).

* Photographed on multiple occasions wearing no underwear under her miniskirts (November 2006).

* Tearfully shaves her own head in a Los Angeles hair salon, and checks into and out of rehab centers twice before spending a month in a Malibu facility for undisclosed treatment (February 2007).

* Strips down to bra and see-through panties for impromptu dip in the Pacific Ocean near Malibu (June 2007).

* Makes dazed, unrehearsed comeback performance at MTV Video Music Awards (September 2007).

* Ordered by a Los Angeles court to undergo random drug testing based upon evidence of "habitual, frequent and continuous use of controlled substances and alcohol." Ordered to hire a parenting coach (September 2007).

* Charged with hit and run and driving without a valid license stemming from an accident in a Los Angeles parking lot (September 2007).

* Loses custody of two children, Sean Preston, 2, and Jayden James, 1, to Federline (October 2007).

* Hospitalized and placed under evaluation for being under the influence of an unknown substance during a scheduled custody handover of two sons to Federline (January 2008).

(Writing by Jill Serjeant; Editing by Xavier Briand)