Last time it seemed the problem might have been Java, but it seems your java is up to date.

You might wish to try replacing the connection cache called gnutella.net; see lower of page here If LW 4 Will Not Connect (click on the blue link)

BTW if you use Norton firewall you need to decide between Vista's firewall or norton, not use both. And put an exception for FW in the one you use. Norton needs the exception to be re-added with each Norton update & each FW update. You might try adding a sub-rule exception for both TCP & UDP with a wide range of ports for the FW exception.