title: WebClient does not support concurrent I/O operations
body: <p>How can I get this error from with in the DownloadStringCompleted Event? Doesn't that mean, it's finished? Is there another event I can fire this from?</p>
  
  <p>I get this error extremely rarely, but once in a while it will happen on my WP7 phone. I have a web client that I fire over and over, and I fire it again from the completed event. Is this happening because there is still some stale connection open? Is there a way to prevent this 100%?</p>
  
  <p>I have checked to see if there is a chance for the thread to walk over itself, but it is only fired from within the completed event.</p>
  
  <p>How can I be sure, when the complete event is fired, the client is no longer isBusy? One suggestion was to add a while with a thread sleep while the client is busy.</p>
  
  <p>Some pseudo code.</p>
  
  <pre><code>var client = new WebClient("URL 1");
  client.CompletedEvent += CompletedEvent;
  client.downloadasync();
  
  void CompletedEvent(){
  Dosomestuff;
  client.downloadasync(); //This is where we break.
  }
  </code></pre>