Secondly, reminders are only activated from within the primary. The Calendar or Task reminder must be in your primary folder, the primary folder being where you receive your messages.

For example, if emails are received in a personal folder (the primary location), and a Task reminder is set up on the Exchange mailbox location, the reminder wouldn't be received because the personal folder is set as the primary, not the Exchange mailbox location.

If you have a need to receive reminders for other locations, e.g. personal folders, and even being notified via pager or cell phone, then check out Slipstick's Web site for some great add-ins for reminders http://www.slipstick.com/addins/calendar.htm.

Thirdly, the reminders folder could be damaged or contain corrupted reminder items. This can be resolved by doing the following: Quit Outlook and select Start->Run. Type "outlook /cleanreminders" (without the quotes), and select OK. This is a common fix for the issues addressed in this article and should clean any corrupted items from your reminder folder.

Finally, if you're running on Microsoft Exchange Server, it's possible the message store is damaged. Create a new mailbox on the server to resolve the behavior. However, before going this route check all of the above on the client (Desktop) side first.