I am trying to access a URI through HttpWebRequest and am getting the "target machine actively refused" error. I know from a machine that has no proxy this works fine and i know my corp internet uses a PAC file to determine the proxy however it doesnt seem to be picking this up for me. Here is what i know: My app.config has I presume i dont need to specify WebRequest.DefaultWebProxy but that makes no difference I can explictly set the proxy with WebProxy and NetworkCredentials which works Any ideas? Anybody have experience with PAC files and why I can access the target through IE but not through code. obviously if i hardcode the proxy it all works so it would seem that this same proxy is not being auto detected?