I've getting a strange error while trying to connect to my CRM2011 server with the Developer's Toolkit. The error/message is just a small box that says "0". That's right! a
ZERO! Not even text in the title of the dialog.
Yeah the message is not helpful. The message box was supposed to show you the "message" of the exception that occurred while trying to get a Server Connection.
Have you provided the correct discovery server name? Use Fiddler and see if it is trying to correct the correct discovery service URL.