The story of Microsoft’s lost decade could serve as a business-school case study on the pitfalls of success. For what began as a lean competition machine led by young visionaries of unparalleled talent has mutated into something bloated and bureaucracy-laden, with an internal culture that unintentionally rewards managers who strangle innovative ideas that might threaten the established order of things.

By the dawn of the millennium, the hallways at Microsoft were no longer home to barefoot programmers in Hawaiian shirts working through nights and weekends toward a common goal of excellence; instead, life behind the thick corporate walls had become staid and brutish. Fiefdoms had taken root, and a mastery of internal politics emerged as key to career success.

In those years Microsoft had stepped up its efforts to cripple competitors, but—because of a series of astonishingly foolish management decisions—the competitors being crippled were often co-workers at Microsoft, instead of other companies. Staffers were rewarded not just for doing well but for making sure that their colleagues failed. As a result, the company was consumed by an endless series of internal knife fights. Potential market-busting businesses—such as e-book and smartphone technology—were killed, derailed, or delayed amid bickering and power plays.

That is the portrait of Microsoft depicted in interviews with dozens of current and former executives, as well as in thousands of pages of internal documents and legal records.

“They used to point their finger at IBM and laugh,” said Bill Hill, a former Microsoft manager. “Now they’ve become the thing they despised.”