This means NetworkActiv AUTAPF was unable to listen on the selected local interface IP address and/or local port. Follow these guidelines: • Make sure the selected local interface IP address is valid: You can do this on the configuration dialog for the selected entry (right-click and choose Edit). Currently available local interface IP addresses show in the Local interface IP address drop-down list. • Make sure the selected local port is not in use (by another port forwarding operation, another instance of AUTAPF, or any other program(s)). This may be done by going to the command prompt and typing netstat -n -a. By default, the command prompt shortcut is located in Accessories; Windows 98/ME users, click Start, open Run… and type command.com, Windows 2000 (and higher) users, click Start, open Run…, type cmd.exe, and then press the Enter key. • For certain protocols and/or ports, you may need to be logged-on with an Administrative user account.