Windows XP SP3 auto enables the Firewall on new Network Connection. You will need to disable the Firewall for the Bluetooth Network connection to pair a Wasp Bluetooth enabled scanner.
To disable the Firewall, navigate to the Control Panel. In the Control Panel double click Network Connections. In Network Connections right click Bluetooth Network Connection and click Properties. In Bluetooth Network Connection Properties click the Advanced tab, then Setting. In the Windows Firewall page set the Firewall to Off. Then setup your Bluetooth scanner with no pass key.