title: Upgrade to .Net 4.5 causes assembly to fail?
body: <p>I've got a project that targets .Net 4.0, and one of the referenced assemblies is .Net 4.5.</p>
  
  <p>Until I installed .Net 4.5 this was working fine, however after the install I get five warnings regarding the targeted .Net version along these lines:</p>
  
  <blockquote>
    <p>*<em>The primary reference "xxxx.Library, Version=1.0.0.1, Culture=neutral, processorArchitecture=MSIL" could not be resolved
    because it was built against the ".NETFramework,Version=v4.5"
    framework. This is a higher version than the currently targeted
    framework ".NETFramework,Version=v4.0"</em></p>
  </blockquote>
  
  <p>And this:</p>
  
  <blockquote>
    <p><em>The primary reference "Microsoft.TeamFoundation.Build.Workflow, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a,
    processorArchitecture=MSIL" could not be resolved because it has an
    indirect dependency on the framework assembly "System.IO.Compression,
    Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"
    which could not be resolved in the currently targeted framework.
    ".NETFramework,Version=v4.0". To resolve this problem, either remove
    the reference "Microsoft.TeamFoundation.Build.Workflow,
    Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a,
    processorArchitecture=MSIL" or retarget your application to a
    framework version which contains "System.IO.Compression,
    Version=4.0.0.0, Culture=neutral,
    PublicKeyToken=b77a5c561934e089". Tests</em></p>
  </blockquote>
  
  <p>Why does Visual Studio hate me?  If it could compile before the update to 4.5, the targeted framework has not changed and it still works for a colleague on VS2010 with .Net 4 why am I being stuffed?</p>