That happened to one of our users. I read through the threads and did the following as suggested:
I reset the user profile but didn't solve problem.
I downloaded MFCMAPI for 32 bit and run the tool from user login. Then I browsed to Root Container and deleted all reminders.
Run command "C:\Program Files\Microsoft Office\Office14\outlook.exe" /resetfolders in command promp and open Outlook again. It worked after doing test reminder.
The only thing that I had trouble with was restoring the deleted reminders to Calender. I have moved them to Deleted Items.
Is there a way to backup the reminders and import them again to Outlook Calender after removing them with MFCMAPI? When I deleted them I chose the option so that all reminders are moved to Deleted Items folder.
Thanks