title: Unable to launch the ASP.NET Development server because port '1900' is in use
body: <p>I was developing just fine in VS 2008 and testing my ASP.NET web site on my development server when suddenly I was unable to run my web site anymore. As soon as I hit F5, the message appears: </p>
  
  <blockquote>
    <p>Unable to launch the ASP.NET Development server because port '1900' is in use. </p>
  </blockquote>
  
  <p>It doesn't matter what port I change to, it's always in use. I have tried:</p>
  
  <ul>
  <li>Changing the port number</li>
  <li>Restarting Visual Studio </li>
  <li>Rebooting my machine</li>
  <li>Installing IIS</li>
  </ul>
  
  <p>Clue: My IIS refuses to start. But I didn't have IIS installed when I was happily working earlier, so that is probably not the issue; it might just be highlighting something else.</p>
  
  <hr>
  
  <p>Update: after rebooting, IIS does start, but the problem here persists.</p>