This paper presents an automata-based approach for analyzing traces generated by the kernel of an operating system. We identified a list of typical patterns of problematic behavior, to look for in a trace, and selected an appropriate state machine language to describe them. These patterns were then fed into an off-line analyzer which efficiently and simultaneously checks for their occurrences even in traces of several gigabytes. The checker achieves a linear performance with respect to the trace size. The remaining factors impacting its performance are discussed.