In a workflow management system, appropriate allocation of its activities greatly contributes to the improvement of its efficiency. We have proposed OXTHAS, a loadbalancing method of scheduling the activities in workflow management systems using Web-services. The OXTHAS makes the activities to be assigned to appropriate executors based on the estimation of their processing capacity using execution histories in workflow engines. In this paper, we propose a failure-aware re-scheduling method for the OXTHAS using process time-outs under network and system failures. To allocate activities appropriately, the estimated processing capacity and time-out duration are re-calculated with consideration of the penalty for a failure when a process time-out occurs. We then evaluate the effectiveness of the proposed methods through simulations.