title: Visual Studio Editor does not underline errors anymore
body: <p>My Visual Studio (2008) Editor has stopped to underline Errors (this nifty wavy red lines). I can't really tell when, but it can be related to the installation of .Net Framework 3.5 SP 1 or the MVC Beta (which I guess is unlikely). Furthermore have I installed and uninstalled both CodeRush and Resharper for evaluation purposes (decided not to keep either one of them).</p>
  
  <p>Does anyone know the problem and how to restore this functionality again?</p>