Every so often, users report this error.  It is from Infragistics.WPF4.Controls.Menus.XamDataTree 14.2.  It looks like there is an internal error happening in the XamDataTree, but I (so Far) haven't been able to reproduce it.  What does this stack trace mean?  Every time i run the offending process, it works fine.

System.NullReferenceException: Object reference not set to an instance of an object.

   at Infragistics.Controls.Menus.IntermediateNodesManager.get_DataCount()

   at Infragistics.Controls.Menus.NodesManager.Infragistics.IProvideDataItems<Infragistics.Controls.Menus.XamDataTreeNode>.get_DataCount()

   at Infragistics.Collections.BindableItemCollection`1.GetCount()

   at Infragistics.Collections.CollectionBaseEnumerator`1.System.Collections.IEnumerator.MoveNext()

   at Infragistics.AutomationPeers.XamDataTreeNodeAutomationPeer.GetChildrenCore()

   at System.Windows.Automation.Peers.AutomationPeer.EnsureChildren()

   at System.Windows.Automation.Peers.AutomationPeer.UpdateChildrenInternal(Int32 invalidateLimit)

   at System.Windows.Automation.Peers.AutomationPeer.UpdateChildren()

   at Infragistics.AutomationPeers.XamDataTreeNodeAutomationPeer.Node_PropertyChanged(Object sender, PropertyChangedEventArgs e)

   at System.ComponentModel.PropertyChangedEventHandler.Invoke(Object sender, PropertyChangedEventArgs e)

   at Infragistics.DependencyObjectNotifier.OnPropertyChanged(String propertyName)

   at Infragistics.Controls.Menus.XamDataTreeNode.OnElementReleased(XamDataTreeNodeControl element)

   at Infragistics.DependencyObjectRecyclingContainer`1.Infragistics.ISupportRecycling.OnElementReleased(FrameworkElement elem)

   at Infragistics.RecyclingManager.PanelInfo.ReleaseElement(ISupportRecycling obj)

   at Infragistics.Controls.Menus.Primitives.NodesPanel.ReleaseNode(XamDataTreeNode node, Boolean removeManager)

   at Infragistics.Controls.Menus.Primitives.NodesPanel.ResetNodes(Boolean releaseAll)

   at Infragistics.Controls.Menus.XamDataTree.XamDataTree_Unloaded(Object sender, RoutedEventArgs e)

   at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)

   at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)

   at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)

   at System.Windows.UIElement.RaiseEvent(RoutedEventArgs e)

   at System.Windows.BroadcastEventHelper.BroadcastEvent(DependencyObject root, RoutedEvent routedEvent)

   at System.Windows.BroadcastEventHelper.BroadcastUnloadedEvent(Object root)

   at MS.Internal.LoadedOrUnloadedOperation.DoWork()

   at System.Windows.Media.MediaContext.FireLoadedPendingCallbacks()

   at System.Windows.Media.MediaContext.FireInvokeOnRenderCallbacks()

   at System.Windows.Media.MediaContext.RenderMessageHandlerCore(Object resizedCompositionTarget)

   at System.Windows.Media.MediaContext.RenderMessageHandler(Object resizedCompositionTarget)

   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)

   at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)