title: Cannot find System.Xaml?
body: <p>I have a VS2010 project that needs a reference to System.Xaml.  I go to the Add Reference, search the .NET references and it's not there. :?</p>
  
  <p>I double checked the GAC too, and no such luck. </p>
  
  <p>I just can't figure out for the life of me why it's not on the machine.  This machine has .NET 3.5 SP1 and .NET 4.0 installed. </p>
  
  <p>I'd much rather there be a simple explanation for this problem and not have to resort to reinstalling the framework. T-T</p>
  
  <p>Any thoughts? Much appreciated.</p>