A program product is embedded in a media accessible by a computer operative to request a plurality of program tasks for wakeup so as to execute the plurality of program tasks in a predetermined schedule. The program product causes at least one of the computer and another computer to execute the instructions of measuring a delay period between a request of at least one of a plurality of program tasks and a wakeup thereof. The instructions include comparing the measured delay period with a predetermined first timeout value, thus determining whether at least one of the plurality of tasks is abnormally executed by the computer based on the comparison result.