Eduardo Saverin: “You're Out.”

Breaking up is hard to do. Especially with millions of dollars of venture capital at stake. Co-founder conflict is an all-too common reason entrepreneurs either dissolve startups or fundamentally alter their core management teams. Just ask Eduardo Saverin, Mark Zuckerberg's co-founder of thefacebook, the Harvard-based social networking site that eventually became Facebook.

From the start, notes venture capitalist and fellow Harvard alum Larry Cheng, Zuckerberg and Saverin brought fundamentally different approaches to managing their fledgling startup, which at that time was limited to Harvard students and grads. Zuckerberg, the programmer, “exuded a killer instinct” and “was not shy about sharing his aspirations of dominating the college market.” Saverin, who incorporated and managed thefacebook from their dorm, was “jovial, likeable, and the fast follower.”^a Founders with these style differences can and do complement each other, but only when they stick together.