title: TFS - Project File was not found
body: <p>I have a large solution in TFS that consists of 28 projects. The build definition currently does a full build each time, and works correctly. I changed "Clean Workspaces" to "None" in an attempt to enable incremental builds, but when I queue a new build after changing the definition it fails immediately with the following message:</p>
  
  <pre><code>Exception Message: The project file 'E:\Builds\43\154\Sources\MyProject\Project.smproj' was not found. (type FileNotFoundException)
  Exception Stack Trace:    at System.Activities.Statements.Throw.Execute(CodeActivityContext context)
     at System.Activities.CodeActivity.InternalExecute(ActivityInstance instance, ActivityExecutor executor, BookmarkManager bookmarkManager)
     at System.Activities.Runtime.ActivityExecutor.ExecuteActivityWorkItem.ExecuteBody(ActivityExecutor executor, BookmarkManager bookmarkManager, Location resultLocation)
  </code></pre>
  
  <p>The strange thing is, it works again if I switch "Clean Workspaces" back to "All". This error only crops up when it's set to "None".</p>
  
  <p>What should I be looking for that I'm doing wrong?</p>