If you are unable to connect to Battle.net, this issue can be caused by several different things.
If you are using Windows 2000/XP/Vista/7 please first verify you are playing under an Administrator Account. Some user accounts can be restricted to save the information needed for the games connection and this can cause the connection problem. To find out which user accounts are marked as Administrator accounts, please see the instructions below:
-Click Start > Control Panel and look for an icon called User Accounts.
-Double click this and it should bring up a list of users on your computer.
-Find the user account that matches your user name and have a look in the group column, it may say administrator, power user or user. This is what type of account you are logged on with. If it says administrator you should be ok.
For Windows Vista/7, in order to set the game as Administrator Mode, please follow the steps below:
1. Right click on the game icon.
2. Select "Run as Administrator"
Also make sure you are not running any add-ons or modifications of any kind. These have also been known to cause connection issues. If such programs exist please completely remove them from your system. In some cases you may need to reinstall the game. If the issue continues please try each of the steps below.
Please try to connect to all four Battle.net Realms (USEast, USWest, 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 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
Battle.net Server List:
Your Realm or Gateway selections may have been altered in some way. This will prevent you from connecting to a Blizzard Entertainment Battle.net server. For instructions on restoring the correct server list for Diablo II, Warcraft II, and StarCraft, please go to this page ("http://us.blizzard.com/support/article/21138").
Internet connection notes:
Firewalls, Routers, and Internet Connection Sharing
* If you are using any type of firewall, router, or you are sharing your internet connection between several computers, you may need to set your system up to allow access to Battle.net. For instructions on setting up your connection, please visit our Networking Help page - ("http://us.blizzard.com/support/article/21086").