What’s the best way to preserve your healthy company culture?

Ben Horowitz (Co-Founder & Partner @ Andreessen Horowitz)
How to Minimize Politics in Your Company – Ben’s Blog

If [when people complain about a co-worker] they are telling you something that you already know, then the big news is that you have let the situation go too far. Whatever your reasons for attempting to rehabilitate the wayward executive, you have taken too long and now your organization has turned on the executive in question. You must resolve the situation quickly. Almost always, this means firing the executive.