title: HttpContext.Current.Session values disappear
body: <p>I have an ASP.NET MVC application.
  For some users we have the problem that from time to time their session context (in <code>HttpContext.Current.Session</code>) disappears (is cleared).
  The session state element in the <code>web.config</code> looks like this:</p>
  
  <pre><code>&lt;sessionState mode="StateServer" timeout="320" /&gt;
  </code></pre>
  
  <p>I check if session timed out like this:</p>
  
  <pre><code>HttpContext.Current.Session.IsNewSession
  </code></pre>
  
  <p>But this was not the case. The values just disappeared.</p>
  
  <p>What can cause this to happen? Could local settings influence the session context?</p>