I would recommend removing the profile and re-adding it, this should eliminate the issue. If you don't wish to refresh the profile, this is achievable by changing the registry key, but this is not advised unless you know what you are doing.

The key which would need changing -
HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows Messaging Subsystem\Profiles\<profile name>\0a0d020000000000c000000000000046

Delete the value name, this should be 0003036f, although it will be different depending on which version of Outlook you had when creating the profile.