title: NullReferenceException in comboBox_SelectedIndexChanged
body: <pre><code>private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
  {
      Dictionary&lt;string, LivePacketDevice&gt; copyOfAdapters = find_adapter.Adapters;
      copyOfAdapters.Remove(comboBox1.SelectedText);
      Dictionary&lt;string, LivePacketDevice&gt; copyOfAdapters22 = copyOfAdapters;
  
  }
  </code></pre>
  
  <p>After start project the exeption is throwed</p>
  
  <blockquote>
    <p>An exception of type 'System.NullReferenceException' occurred in ...... but was not handled in user code</p>
    
    <p>Additional information: Object reference not set to an instance of an object.</p>
  </blockquote>
  
  <p>at the end of first line of method. But <code>find_adapter</code> was created in constructor of the Form. So where is mistake?
  I really do not know :/
  THX</p>