New Post: Reminder won't Delete

I have one user that is constantly getting reminders of an appointment long gone.  She can't snooze, dismiss, etc.  I tried to delete the reminder with MAPI, but I get the following errors when I click on the message:

Error:

Code: MAPI_E_INVALID_ENTRYID == 0x80040107

Function DefaultOpenItemProp( iItem, mfcmapiDO_NOT_REQUEST_MODIFY, lppProp)

File ContentsTableListCtrl.cpp

Line 1467

Error:

Code: MAPI_E_INVALID_ENTRYID == 0x80040107

Function m_lpContentsTableListCtrl->DefaultOpenItemProp( iSelectedItem, bModify, lppMAPIProp)

File ContentsTableDlg.cpp

Line 820

I can right-click and delete, change the drop down to any of the 3 choices, but the message will not delete.  It just stays there.  I even tried running as an admin, with no luck. 

Any suggestions?