title: Cannot add System.Web.dll reference
body: <p>I'm trying to use the HTTP functions contained in the System.Web.dll assembly. However, whilst the dll seems to exist in the same directory as every other dll Visual Studio 2010 references in my project, it fails to link in and raises a warning - "The referenced component 'System.Web' could not be found". The dll, however, is definitely there within the same folder as all others referenced by the project and selecting it in 'browse for reference' mode allows me to add it - it then fails to fill in the 'Path' property. Am I doing something wrong? How can I make System.Web available in my project?</p>
  
  <p>Any help is much appreciated!</p>
  
  <p><strong>Edit:</strong> I don't have any reference to System.Web in the .Net tab of the 'Add Reference' window.</p>