Issue with Exchange 2010 Autodiscover

A Web exception occurred because an HTTP 404 - NotFound response was received from IIS6.
Headers received:
MicrosoftOfficeWebServer: 5.0_Pub
Content-Length: 1635
Content-Type: text/html
Server: Microsoft-IIS/6.0
X-Powered-By: PleskWin,ASP.NET
Date: Mon, 26 Aug 2013 15:27:03 GMT

	Attempting to send an Autodiscover POST request to potential Autodiscover URLs.
	Autodiscover settings weren't obtained when the Autodiscover POST request was sent.
	Test Steps   The Microsoft Connectivity Analyzer is attempting to retrieve an XML Autodiscover response from URLhttps://autodiscover.domain.org/AutoDiscover/AutoDiscover.xml for user user@domain.org.   The Microsoft Connectivity Analyzer failed to obtain an Autodiscover XML response.   Additional Details   An HTTP 401 Unauthorized response was received from the remote Unknown server. This is usually the result of an incorrect username or password. If you are attempting to log onto an Office 365 service, ensure you are using your full User Principal Name (UPN). Headers received: Content-Type: text/html Server: Microsoft-IIS/7.5 WWW-Authenticate: Basic realm="autodiscover.domain.org",Negotiate,NTLM X-Powered-By: ASP.NET Date: Mon, 26 Aug 2013 15:27:05 GMT Content-Length: 58