THE day after her autobiography was published, the cover of Newsweek magazine asked the musical question, "How Do You Solve a Problem Like Sarah?" It's a play on the first line of the chorus of "Maria" in the musical, "The Sound Of Music."The nuns sing of their bewildering young charge, who not only marches to the beat of her own drummer, but sings, dances and strums guitar to it. Their solution is to ship her off to a household in need of a nanny, and thus one of the most extraordinary adventures of the 20th century begins. There is a...