Which software firewall are you using?

Which version of Java are you using?

Where are you connecting from (house, apartment, work, school, student accommodation etc)?

If there were any fixes in the 'if LW 4 Will Not Connect' thread that you didn't try, please tell us which ones.

After deleting LW's preferences folder, did you have to go through the setup wizard again?
Did you replace or delete your gnutella.net file, or both? Find your gnutella.net file & hover your cursor over the file - how big is it?
Are you using the HomeHub with UPnP enabled or a port forwarded?

If you haven't tried port forwarding, the instructions are here: Port Forwarding for the BT Home Hub
Use a high port number (eg 65000). LW's listening port, port in the 'manual port forward' box & port forwarded within the HH setup must all be the same number.

Before port forwarding, most routers require you to set up a static IP address for your computer. There's no mention of that in the HH port forwarding instructions so I assume it isn't necessary