A while back I was trying to consume some XML from a third party site and I found myself getting stuck on an error.  The site would not give me a valid response and would throw up a 403 error.  After digging around I found that I left off the user-agent info in the request header.  So the moral to this story is: Don't forget your user-agent!

Code Sample after the break.
 

   1:  try

   2:  {

   3:      //Get the Document from the url.

   4:      WebClient client = new WebClient();

   5:      client.Headers.Add("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705;)");

   6:      doc.LoadXml(client.DownloadString(SourceXML));

   7:      

   8:      

   9:      ...

  10:      ...

  11:      ...

  12:   

  13:  }