title: Silverlight WSOD at remote client site
body: <p>I have a client who installed our silverlight app recently.  it works fine from their server itself.  but when they try to run it from a client, they can log in through the aspx login page, but on the main page, which hosts the  tag and the .xap file, they see absolutely nothing!</p>
  
  <p>I cannot see their screens, just get occasional screenshots via email and cross my fingers that they are typing the URL I tell them to.  Even Shareview is not working for them - they can see my screen but I cannot see theirs.</p>
  
  <p>So I am pleading - help!  Please throw out some wacky ideas.   I just learned an hour or so ago that they did not even have silverlight installed, so the mornings debugging effort was a waste of time. So who knows what the next fascinating source of problems is?</p>
  
  <p>Here is the user-agent info.  Oor app is .net 4.0  could that be the problem?  It does noty look to my untrained eye that the client supports 4.0 (from the web server log):</p>
  
  <p>Mozilla/4.0+(compatible;+MSIE+7.0;+Windows+NT+5.1;+.NET+CLR+1.1.4322;+.NET+CLR+2.0.50727;+.NET+CLR+3.0.04506.30;+.NET+CLR+3.0.04506.648;+.NET+CLR+3.0.4506.2152;+.NET+CLR+3.5.30729) 401 3 5 0</p>
  
  <p>Getting closer - I see that the GET request for the XAP is returning 401 - not found!  What would do that?</p>