DoubleClick announced late tonight that it hired Lazard Freres & Co. to explore how to shake up its business by doing something radical to its corporate structure. Among the options listed in the announcement were a sale of all or parts of the company, a recapitalization, spin-off or an extraordinary dividend. DoubleClick - a dominant force in the first Internet boom - has been largely left out of the mega growth in the ongoing second boom because it sold its media business when online media went out of fashion among investors.