The logon functionality relies on a security key provided by your Internet or Broadband Service Provider (ISP or BSP). For the logon box to appear, port 443, the secure socket layer, has to be open. If you think this may be the problem you should first contact your ISP/BSP to ask if this port is open.

If you have made any transactions online (for example purchased something from Amazon) this will also have needed the same port open to send your credit details securely.