title: What does "GLib-GObject-WARNING **: instance with invalid (NULL) class pointer" mean?
body: <p>Whenever I close my Gtk# application, I get this:</p>
  
  <pre><code>(/home/matthew/opensbs/OpenSBS/bin/Debug/OpenSBS.exe:5050): GLib-WARNING **: g_set_prgname() called multiple times
  
  (/home/matthew/opensbs/OpenSBS/bin/Debug/OpenSBS.exe:5050): GLib-GObject-WARNING **: instance with invalid (NULL) class pointer
  
  (/home/matthew/opensbs/OpenSBS/bin/Debug/OpenSBS.exe:5050): GLib-GObject-CRITICAL **: g_signal_handlers_disconnect_matched: assertion `G_TYPE_CHECK_INSTANCE (instance)' failed
  
  (/home/matthew/opensbs/OpenSBS/bin/Debug/OpenSBS.exe:5050): GLib-GObject-WARNING **: instance with invalid (NULL) class pointer
  
  (/home/matthew/opensbs/OpenSBS/bin/Debug/OpenSBS.exe:5050): GLib-GObject-CRITICAL **: g_signal_handlers_disconnect_matched: assertion `G_TYPE_CHECK_INSTANCE (instance)' failed
  
  (/home/matthew/opensbs/OpenSBS/bin/Debug/OpenSBS.exe:5050): GLib-GObject-WARNING **: instance with invalid (NULL) class pointer
  
  (/home/matthew/opensbs/OpenSBS/bin/Debug/OpenSBS.exe:5050): GLib-GObject-CRITICAL **: g_signal_handlers_disconnect_matched: assertion `G_TYPE_CHECK_INSTANCE (instance)' failed
  
  (/home/matthew/opensbs/OpenSBS/bin/Debug/OpenSBS.exe:5050): GLib-GObject-WARNING **: instance with invalid (NULL) class pointer
  
  (/home/matthew/opensbs/OpenSBS/bin/Debug/OpenSBS.exe:5050): GLib-GObject-CRITICAL **: g_signal_handlers_disconnect_matched: assertion `G_TYPE_CHECK_INSTANCE (instance)' failed
  
  (/home/matthew/opensbs/OpenSBS/bin/Debug/OpenSBS.exe:5050): GLib-GObject-CRITICAL **: g_object_ref: assertion `object-&gt;ref_count &gt; 0' failed
  </code></pre>
  
  <p>I'm not really sure what's going on here. I found one person with a similar problem on google, but they seemed to be a user of an application, not a developer. An ideas?</p>