title: Visual Studio popup: "the operation could not be completed"
body: <p>When I try to open a project, local or on a <a href="https://en.wikipedia.org/wiki/Team_Foundation_Server" rel="noreferrer">Team Foundation Server</a> (TFS), I get a modal window telling me that:</p>
  
  <blockquote>
    <p>The operation could not be completed: Unspecified error</p>
  </blockquote>
  
  <p>Or the same message, but with "Class not defined.." instead of "Unspecified error".</p>
  
  <p>These errors started happening earlier today when I tried to check in some of my work to the team foundation server. I have tried using Visual&nbsp;Studio&nbsp;2008 on the same computer, but I still get the same error. I've also googled for it but none of the solutions seems to help me.</p>
  
  <p>I have installed the latest updates from Windows Update as well.</p>
  
  <p>Any ideas?</p>