When installing OCS 2007 R1 and R2 Enterprise edition server the validation of the Application Sharing Server or Web Conferencing Server fails with the error code
Received a failure HTTP response.: Unauthorized
[0xC3FC200D] One or more errors were detected
I have encountered this problem several times now and in my case this was a problem where IIS blocked local access when you use the fully qualified domain name (FQDN) or a custom host header to browse a local Web site that is hosted on a computer that is running IIS. You may receive an error message similar to the following: “HTTP 401.1 – Unauthorized: Logon Failed.” If you try the same URL from an other computer you should be able to access the site so it is not a critical problem.
If you want to fix this so that your validations don’t fail, configure IIS to allow enterprise pool FQDN for loopback:
- Click Start, click Run, type regedit, and then click OK.
- In Registry Editor, locate and then click the following registry key:
- Right-click MSV1_0, point to New, and then click Multi-String Value.
- Type BackConnectionHostNames, and then press ENTER.
- Right-click BackConnectionHostNames, and then click Modify.
- In the Value data box, type the FQDN of your enterprise pool, and then click OK.
- Close Registry Editor, and then restart the IISAdmin service.
Resolution found over at Technet http://technet.microsoft.com/en-us/library/dd441168(office.13).aspx