title: Visual Studio Build Error:requested operation cannot be performed on a file with a user-mapped
body: <p>If I open visual studio build and then build again I always get this error.</p>
  
  <pre><code>  requested operation cannot be performed on a file with a user-mapped 
  </code></pre>
  
  <p>then I have to restart visual studio and go through it all over again. This just recently started happening any ideas why ?</p>
  
  <p>Machine - Visual Studio 2010, Windows 7</p>