The specific nature of the problem is that a reminder for old appointments will pop up shortly after opening Microsoft Outlook due to some of the Corrupted entries in the Calendar.
Follow the workaround mentioned below to fix this issue.
1. Begin by selecting the Calendar folder and then select View -> Current View -> All Appointments to see a list of all of your past, present and future appointments.
2. The trick now is to sort through the list until you find the damaged calendar entry. The corrupt appointments should be pretty easy to spot, because they will have the same names as the appointments that you see each time you open Microsoft Outlook.
3. Delete the corrupt Microsoft Outlook appointment.
You will see a dialog box filled with a series of error messages telling you that the appointment cannot be deleted, recurrence information cannot be located, and that the sender may not receive updates to the appointment. In spite of these errors, the Microsoft
Outlook appointment will be deleted anyway.