I have been involved in many startups, some successful and some not so successful. When a team of founders gets crosswise its a harbinger of real trouble. You can sit down with your cofounders and discuss the problem openly and hope that you can solve the problems by everyone agreeing. However, unless you have un-vested stock, or contracts that require a certain amount of contribution, or some other leverage, you are reduced to mere persuasion without any leverage. If you would like to discuss this further, please feel free to get in touch with me.