Proactive service assurance depends on the ability to anticipate problems in a network. This paper presents a system to forecast high-severity system event messages before they occur. Forecasts are based on a stream of syslog messages from devices, which is compared and scored against a set of codes that are representative of known problem event patterns. The system includes a component to mine relevant event patterns from past problem occurrences. In addition to describing the techniques and algorithms that the system is based on, the paper also provides an assessment of the effectiveness of those techniques.