Untick it, and then enter "http://127.0.0.1:8080". The subsonic org is the subsonic.org address. Your address is prc56.subsonic.org. If you have subsonic running with the port set to 8080 and https off, it will work after typing "http://127.0.0.1:8080" on the server.
The firewall won't block your own computer from accessing itself.
