ERROR: Number of delayed events during past 24 hours exceede

We are encountering the attached errors though we have adjusted the config file settings already.  We are doing a task management system for a 3 shifts of 24/7 hospital operation. All tasks of the care givers, nurses, doctors, etc. is being handled by the system. Each task has a start date and time attribute. Once a particular task reaches its scheduled time, it will notify/remind the task owner. It has also an end date and time attribute to determine which tasks are not done by the task owner on schedule to carry over to the next shift and assign to the new task owner. These notifications/reminders/carry over are executed by triggers. The rest of the functionalities work properly except that before the end of the day, we encountered the attached problem.

Btw, our engine version is 4.08. Need help to address this problem ASAP.