Hi,
Check your firewall; make sure that port is open. Most firewall software will detect the connection attempt and prompt you to allow/disallow the connection. You might also need to forward that port through your router. I don’t know what model router you have, but this might help: http://portforward.com/english/routers/port_forwarding/Sitecom/WL-153/iTunes.htm. I’ve also heard this is overkill, but it probably can’t hurt to try.
Hope this helps!
