Prueba el Battle.net Diagnostic Tool
http://win32.lordaeron.org/BnetDiagTool.html
También podrias estar baneado:
Step 2: Temporary Restrictions
Please try to connect to all four Battle.net Realms (US East, US West, Europe, and Asia). If only one Battle.net Realm is inaccessible to you, then it may just be a temporary connection problem or a temporary restriction. Battle.net access may be restricted (up to 1-2 days) for one of the following reasons:
Spamming text in the chat channel (often associated with bots)
Rapidly connecting/disconnecting to Battle.net (often associated with bots)
Repeated attempts to use an invalid CD-Key or an incorrect Battle.net password
Repeated use of third-party programs (hacks). These include, but are not limited to, sending bad packets, flooding the server(s), and the use of hack programs
O simplemente tener algún problema con la selección de la puerta de enlace del server.
Mira las recomendaciones de Blizzard en su web y nos dices que ha sido.
http://faq.blizzard-europe.com/en/article.php?id=012