Abstract: A paper-handling unit serves for generating groups of items, wherein each group includes a plurality of items. The paper-handling unit includes at least one input channel for receiving the items, a portion to generate groups from the received items, a drive-out station for driving out a generated group, a detector detecting predetermined features from the items of a driven-out group, and a controller. The controller is operable to determine whether a predetermined event has occurred to drive the drive-out station to drive out a group if the predetermined event has occurred, to determine whether information was obtained from the detector during a predetermined interval, to stop the paper-handling unit if no information was obtained from the detector during the predetermined interval, and to stop the paper-handling unit if information was obtained from the detector during the predetermined interval which indicates that the driven-out group does not meet at least one predetermined criterion.