From this link:
http://technet.microsoft.com/en-us/library/cc178973.aspx#section1If you are working in an Access 2003 database but using Office Access 2007, when the Access 2003 database has workgroup security enabled, run as an Administrator. This is no longer on the Ribbon but details can be found in What happened to user-level security? (
http://go.microsoft.com/fwlink/?LinkId=143688).