Hi everyone, A client recently informed us that deployment of our software in their environment has failed due to a proxy error when the software attempts to access the internet. The client has a combination of Citrix and Microsoft's ISA server. The software allows the use of a proxy and the ability to manually enter authentication information, or automatically retrieve the current system proxy settings. The error returned is the standard 407 authentication error, but the client assures us that they have entered the authentication information required. They have also shown us the snippet of the ISA error logs which identify the client as Anonymous and the authentication protocol as Basic. I have a few questions I suppose: How should I go about dealing with the ISA server in my code? I have no real experience with this environment and am assuming that the ISA server is treated like any other proxy. If I am mistaken, what should I be doing? Does ISA allow the administrator to disallow specific authentication protocols - and if this is the case and 'Basic' auth is disallowed, would it still return a 407 error? Could the Citrix environment have caused this issue? Is there any particular way to ensure that my software will work in such an environment? Code-samples would be much appreciated. I have neither a Citrix test server or an ISA server at my disposal to carry out testing on this so I am currently trying to identify possible causes before I make the case for investment in a more robust testing environment. Thanks for any help!