This talk presents a system-oriented view of risks in computer-communication networks. We will address risks relating to security, reliability, and availability (among others) in a wide range of environments -- including not just the Internet and WWW, but also power transmission and distribution, public switched communications networks, air-traffic control, and other critical systems -- and how those risks are interrelated. We will consider what we have and have not learned in the past, and where the major remaining problems are. We will explore common problems and potential approaches, concerning both maliciously and accidentally caused incidents, and consider how to develop a constructive course of action for the future.