Recently came across this error message after migrating a site from Sharepoint 2007 to Sharepoint 2010. Apparently it is an issue where the relationships list is not updated when migrating a site.
The Relationships List can be found at http://(yoursiteurl)/Relationships%20List/allitems.aspx
As the site collection administrator deactivate the SharePoint Server Publishing Infrastructure feature under Site Settings for the site collection that has the issue. Then delete the Relationships List - http://(yoursiteurl)/Relationships%20List/allitems.aspx.
Re-activate the SharePoint Server Publishing Infrastructure feature and the Relationships List will be recreated, this will correct the problem.