title: Downgrade an application from .net 4.0 to 3.5
body: <p>I have been developing an application in VS2010 and compiling it for the .NET 4.0 as the target framework. After integrating a library into my application, I get the following error message when I try to compile:</p>
  
  <blockquote>
    <p>Mixed mode assembly is built against version 'v1.1.4322' of the runtime and cannot be loaded in the 4.0 runtime without additional configuration information.</p>
  </blockquote>
  
  <p>The library works fine under .NET 3.5, but when I change my target framework to .NET 3.5, I get the following error for all my .resx files:</p>
  
  <blockquote>
    <p>Error 1 Object reference not set to an instance of an object.</p>
  </blockquote>
  
  <p>I tried ctrl-h Version=4.0.0.0 to Version=3.5.0.0 but that doesn't seem to work. Is there anything I can do other that create a new application?</p>