Validation of Application Sharing Server or Web Conferencing Server fails :

Lors de l'installation d'OCS 2007 R1 ou R2 Enterprise Edition, lors de la phase de validation du service de partage d'application ou de Conférence Web, l'erreur suivant revient souvent : 

Received a failure HTTP response.: Unauthorized
[0xC3FC200D] One or more errors were detected

Ce n'est pas un problème critique, mais si vous souhaitez le résoudre, il faut suivre la procédure suivante :

1. Click Start, click Run, type regedit, and then click OK.
2. In Registry Editor, locate and then click the following registry key:
3. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\MSV1_0
4. Right-click MSV1_0, point to New, and then click Multi-String Value.
5. Type BackConnectionHostNames, and then press ENTER.
6. Right-click BackConnectionHostNames, and then click Modify.
7. In the Value data box, type the FQDN of your enterprise pool, and then click OK.
8. 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