The ParadoxNetPath value in the \HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Jet\3.5\Engines\Paradox Registry key is not valid. This error occurs if you're using the Paradox external database and the ParadoxNetPath value points to a nonexistent directory. Exit the application, correct the invalid entry, and try the operation again.
The ParadoxNetPath Registry value points to a network drive and you aren't connected to that network drive. Make sure the network drive is available, and then try the operation again.