Proxy authentication required

You must be authenticated by a proxy server before the Web server can execute your request.

Please try the following:

Log on to your proxy server and try again.
Contact the proxy server administrator if you believe you should be able to view this directory or page.

HTTP Error 407 - Initial proxy authentication required by the Web server.
Internet Information Services (IIS)

Technical Information (for support personnel)

Go to Microsoft Product Support Services and perform a title search for the words HTTP and 407.
Open IIS Help, which is accessible in IIS Manager (inetmgr), and search for topics titled Authentication, About WebDAV, and About Custom Error Messages.