This paper considers the minimization of the maximum lateness for a set of dependent tasks with unit duration, unit communication delays release times and due dates. The number of processors is limited, and each task requires one processor for its execution. A time window built from an upper bound of the minimum maximum lateness is associated to each task. The parameter considered is the pathwidth of the associated interval graph. A fixed-parameter algorithm based on a dynamic programming approach is developed to solve this optimization problem. This is, as far as we know, the first fixed-parameter algorithm for a scheduling problem with communication delays and a limited number of processors.