title: MSBUILD fails with "The process cannot access the file xxxxx because it is being used by another process." when maxcpucount is greater than 1
body: <p>I'm trying to improve build times using CruiseControl.NET and MSBUILD, and one of the commandline switches, maxcpucount can be used to allow the build occur in parallel. Our solution has 60+ projects so any improvement would be helpful.  However, whenever I up the maxcpucount above one, we have frequent build failures due to:</p>
  
  <blockquote>
    <p>"The process cannot access the file xxxx because it is being used by
    another process. msbuild"</p>
  </blockquote>
  
  <p>It appears that the additional parallel build threads/processes are locking each other. </p>