title: Visual Studio - Can't close the IDE, create new solutions, or add references
body: <p>I've built a new PC, and installed Visual Studio Community edition on it.</p>
  
  <p>It worked great for a couple days, but around a week later, it has become unusable for the following reasons:</p>
  
  <ul>
  <li>I get 'object reference not set to an instance of an object' when trying to close the IDE! I have to kill devenv.exe from taskmgr.</li>
  <li>I regularly get 'Value cannot be null. Parameter name: compositionService' when trying to add references. I simply can't add references</li>
  <li>I get 'object reference not set to an instance of an object' when trying to create a new solution.</li>
  </ul>
  
  <p>I have a feeling that all are related to something and finding that something is my goal.</p>
  
  <p>Any advice on how to remedy my IDE? I have no hope of being remotely productive at present!</p>