Gnutella Forums - New and confused (Under advanced tools it saysI am behind a firewall and dont support firwall transfers)

I am using Limewire 5.5.14 Pro,and java ver 1.6.0_21, I have partial dloads that have stopped. Under advanced tools it says I am behind a firewall and dont support firwall transfers. There is a red circle with a ? in it. when i put curser on this it says Lime wire behind a NAT or firewall that asigns different external port to each connection. How can i fix this as it has only just come up. I have the following Windows XP media centre edition Version 2002 service pack 3 with 1gig ram. I have windows firewall with 83 gig free space on Hdrive. Have broadband connection through Bigpond viar Thomson TG782T @ my house in Australia. Port test link says success. I have had LW for a year now and this is new prob. i have ESET NOD32 Antivirus 4 prog. Unsure as to latest updates as wife also uses comp. Also i have full conection as per lower left signal strength on PRO screen. Thanks Tony