Outlook Anywhere Failure - RPC Proxy can't be pinged.

Hello, I am trying to set up Outlook Anywhere on Exchange 2010 SP1 x64, Server 2008 R2 x64, Outlook 2010 x86 (on Windows 7). The Exchange server is the DC and runs all affiliated servers (CAS, Mail etc). 80 and 443 are open to the Exchange Server. Whenever I run "testexchangeconnectivity.com" I get this:

NOTE: I have substituted in contoso for the actual name of the domain.

      Testing RPC/HTTP connectivity.
       The RPC/HTTP test failed.
       
      Test Steps
       
      Attempting to resolve the host name mail.contoso.com in DNS.
       The host name resolved successfully.
       
      Additional Details
       IP addresses returned: 12.34.56.789
      Testing TCP port 443 on host mail.contoso.com to ensure it's listening and open.
       The port was opened successfully.
      Testing the SSL certificate to make sure it's valid.
       The certificate passed all validation requirements.
       
      Test Steps
       
      Validating the certificate name.
       The certificate name was validated successfully.
       
      Additional Details
       Host name mail.contoso.com was found in the Certificate Subject Common name.
      Certificate trust is being validated.
       The test passed with some warnings encountered. Please expand the additional details.
       
      Additional Details
       ExRCA can only validate the certificate chain using the Root Certificate Update functionality from Windows Update. Your certificate may not be trusted on Windows if the "Update Root Certificates" feature isn't enabled.
      Testing the certificate date to confirm the certificate is valid.
       Date validation passed. The certificate hasn't expired.
       
      Additional Details
       The certificate is valid. NotBefore = 8/18/2009 4:36:08 PM, NotAfter = 8/18/2011 4:36:08 PM
      Checking the IIS configuration for client certificate authentication.
       Client certificate authentication wasn't detected.
       
      Additional Details
       Accept/Require Client Certificates isn't configured.
      Testing HTTP Authentication Methods for URL https://mail.contoso.com/rpc/rpcproxy.dll.
       The HTTP authentication methods are correct.
       
      Additional Details
       ExRCA found all expected authentication methods and no disallowed methods. Methods found: Basic, Negotiate, NTLM
      Testing SSL mutual authentication with the RPC proxy server.
       Mutual authentication was verified successfully.
       
      Additional Details
       Certificate common name mail.contoso.com matches msstd:mail.contoso.com.
      Attempting to ping RPC proxy mail.contoso.com.
       RPC Proxy can't be pinged.
       
      Additional Details
       A Web exception occurred because an HTTP 401 - Unauthorized response was received from Unknown.

And I have spent several hours trying to fix it including reinstalling the RPC feature several times and resetting IIS. I've also gone into the registry: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Rpc\RpcProxy (as I've read on some forums) and made sure the registry is correct. (I also have another setup, identical, Ex2010 etc which is working perfectly and have compared registry keys and they all are identical).

ValidPorts: MAIL:593;MAIL:49152-65535;MAIL:6001-6004;mail.contoso.com:6001-6004;mail.contoso.local:6001-6004
ValidPorts_AutoConfig_Exchange: mail:6001-6002;mail:6004;mail.contoso.local:6001-6002;mail.contoso.local:6004

I can also navigate to the .dll at "https://mail.contoso.com/rpc/rpcproxy.dll". It just displays a blank page.