Most wireless devices have internal NAT firewalls. But it appears yours may not have such. To find out more, go to the bottom of the page link here & look at the support links http://whirlpool.net.au/index.cfm?a=h_view&model_id=189

You have XP so I presume you configured it to allow LW access right? (advisable not to have 2 active firewalls b/c they can interfere with each other); Firewall configuration instructions (click on link)

If still problems, try changing listening port to one between 49152 - 65535, such as 64049. To change this, go to LW's menu bar, Tools>Options>Advanced>Firewalls.