After installing Microsoft Office 2010 SP1 or the September 13, 2011 public update for Outlook 2007 (2583910), you notice that you are not getting reminders for your appointments anymore. Also using the flags to mark your follow-up items no longer work. When trying to flag an item for follow-up the item will be marked as completed and the flagged items will not show in the To-Do Bar.
The cause of this issue was a fix that was included in Microsoft Office 2010 SP1 and Public Update 2583910 for Office 2007.
The fix for this is included in the August update for Office 2010. http://support.microsoft.com/kb/2588842
The Outlook 2010 update needed to resolve this issue is available on this KB http://support.microsoft.com/kb/2584053
The Outlook 2007 update needed to resolve this issue is available on this KB http://support.microsoft.com/kb/2553028
Office 2007 Additional Information:
Public Update 2583910 (released September 13, 2011) will update Outlook.exe to version 12.0.6562.5003.
Hotfix Package 2553028 (released August 30, 2011) will update Outlook.exe to version 12.0.6565.5000.
for other considerations.