CRM 2011 - "HTTP 500 - Internal Server Error" using SOAP Endpoint in Silverlight Webresources

Requesting data over organization endpoint results in the following error.
HTTP 500 - Internal Server Error

The problem may be a missing provider-setting in the IIS configuration.


Solution:

• Open IIS Manager
• Select "Microsoft Dynamics CRM" Site
• Doubleclick "Authentication"
• Right click "Windows Authentication"
• Select "Providers"
• Add "Negotiate"
• IIS-Reset

 There should be two "Provider" entries.

• Negotiate
• NTLM

Cheers,
Markus