1. Go in your Diablo III folder.
2. Open the .agent.db file on WordPad.(This file may be hidden and please, do not delete this file)
3. find the "patch_url" line and change its value to:
http://enUS.patch.battle.net:1119/patch4. Save and close the file.
5. Now go in the Battle.net folder:
C:\Document and settings\All Users\Application Data\Battle.net(ProgramData and Application Data are hidden folders.)
6. Once inside the Battle.net folder, select and delete the Agent folder. (don't skip this step)
7. Start the Launcher.