By Brandon Bailey and Pete Carey, San Jose Mercury News, Calif. Jul. 24--The architect of Microsoft's star-crossed effort to buy Yahoo is leaving his job, in an unexpected move that raises questions about the giant software company's continued pursuit of the Sunnyvale Internet firm.

By Brandon Bailey and Pete Carey, San Jose Mercury News, Calif. Jul. 24--The architect of Microsoft's star-crossed effort to buy Yahoo is leaving his job, in an unexpected move that raises questions about the software giant's continued pursuit of the Sunnyvale Internet company.

After years of watching Google run away with Internet search and make billions from the related advertising, Microsoft is trying to tweak the fundamental business model of the industry in its favor.

Microsoft, facing a threat from Google, IBM and other rivals, is ramping up its online services, which are hosted applications that manage such things as e-mail, calendars and video conferencing.

As Microsoft's strategy for linking its past to its future has evolved over the past three years, so too has the team of leaders overseeing that transition.