Turn off Sync Services in Preferences
Quit Outlook and all other applications
On the Apple menu, click Force Quit.
Select an application in the "Force Quit Applications" window.Note: You cannot quit Finder.
Click Force Quit.
Drag OfficeSync Prefs to the Trash, and then close the window.
On the Apple menu, click Restart.
Open Outlook.
On the Outlook menu, click Preferences.
Under Other, click Sync Services.
Select the check boxes for the items that you want to sync.
Close the window.
Back up Outlook identities
Reset Microsoft Sync Services
If you still experience the problem visit this thread.
