Carlos Kleiber, a conductor whose brilliant interpretations of opera and a limited symphonic repertoire were surpassed only by his eccentric, often baffling behavior, died July 13 under a typical shroud of secrecy. Word of his death was not received until he had been buried in Slovenia, beside his wife, Stanka, who died in December. Mr. Kleiber, 74, lived in Munich, but neither the place of his death nor its cause was disclosed. News reports indicated only that he had had a long illness..