Cause: The reminder for a past task or calendar event has not been dismissed.
Solution: Dismiss the reminder.
When the reminder appears again, click Dismiss.
Cause: The reminder is for a recurring task or calendar event.
Solution: Clear the reminder for the event.
Open the event.
On the Meeting tab, click the Reminder pop-up menu, and then click None.
Solution: Clear the reminder for the task.
Open the task.
Click the arrow next to Follow Up, and then click Add Reminder.
Clear the Reminder check box, and then click OK.