The error is happening on Windows XP Home Edition.
Are they using a proxy server?
authenticate()method will not succeed when a user's Internet connection passes through a proxy server requiring authentication. Although such users are not able to preload a DRM voucher that requires authentication, your application can obtain the voucher by beginning playback and using the NetStream
setAuthenticationCredentials()method to log the user into both the proxy and the media rights servers. Once the voucher has been obtained, the user can view the content offline (as long as the license represented by the voucher allows offline playback)."
No. They can authecnticate on other windows machines on the same network.