the linked tables in your datbase should be identified by black arrows for Jet tables, or a world or other symbol for ODBC connections.
if you float over the table, the connection path should be displayed (versions AFTER A97) - In A97, you need to establish the connection details programmatically.
If the path is invalid (perhaps becuase your mapped drives are inconsistent), Access won't be able to find the folder location referred to, in which case you need ot refresh the connections.