A method for diagnosing problems in a computer system by providing a user interface for visualizing flows through subsystems of the computer system, and allowing a user to explore relationships between a triage map which graphically depicts subsystems, and a transaction trace graph, which depicts a time sequence of invoked components of the subsystems. In one aspect, in response to a user selecting a portion of the transaction trace graph which depicts an invoked component, the user interface visually distinguishes one of the subsystems which invokes the invoked component. In another aspect, the transaction trace can be played back so that subsystems in the triage map are highlighted in turn, in a time sequence, as components of different subsystems are invoked. A time marker can skip to selected time points which result in updating of the triage map.