It is a challenging task to reason about a dynamically evolving system with events triggering state transitions and uncertainty about the ordering of events. In previous research, uncertainty of the event ordering is mainly modelled by partial orders over the events. In this paper, we investigate uncertainty of the event ordering modelled by time intervals in which the events may occur. Each event will occur at exactly one point of time, but it could be any point within the time interval associated with the event. We present both positive and negative results that provide insight into the complexity of temporal reasoning about events with time-interval information.