Another bug: if we create a simple grid with many rows, use RecordContainerGenerationMode = Virtualize, then hold down the scroll down button on the grid for a while, we get an exception thrown (see the detailed CallStack further down).  This setting is apparently necessary to fix alternate row styling display per another post.

System.InvalidOperationException was unhandled
  Message="Range of Remove(0,11) cannot include items without a corresponding user interface element."
  Source="PresentationFramework"
  StackTrace:
       at System.Windows.Controls.ItemContainerGenerator.System.Windows.Controls.Primitives.IItemContainerGenerator.Remove(GeneratorPosition position, Int32 count)
       at Infragistics.Windows.Virtualization.RecyclingItemsPanel.CleanupUnusedGeneratedElements()
       at Infragistics.Windows.Virtualization.RecyclingItemsPanel.a(Object A_0, EventArgs A_1)
       at System.Windows.Threading.DispatcherTimer.FireTick(Object unused)
       at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter)
       at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler)
       at System.Windows.Threading.DispatcherOperation.InvokeImpl()
       at System.Windows.Threading.DispatcherOperation.InvokeInSecurityContext(Object state)
       at System.Threading.ExecutionContext.runTryCode(Object userData)
       at System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData)
       at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Windows.Threading.DispatcherOperation.Invoke()
       at System.Windows.Threading.Dispatcher.ProcessQueue()
       at System.Windows.Threading.Dispatcher.WndProcHook(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
       at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
       at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
       at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter)
       at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler)
       at System.Windows.Threading.Dispatcher.InvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Boolean isSingleParameter)
       at System.Windows.Threading.Dispatcher.Invoke(DispatcherPriority priority, Delegate method, Object arg)
       at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)
       at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg)
       at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame)
       at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame)
       at System.Windows.Threading.Dispatcher.Run()
       at System.Windows.Application.RunInternal(Window window)
       at System.Windows.Application.Run(Window window)
       at System.Windows.Application.Run()
       at QiiuTmsParts_Test_App.App.Main() in C:\Qiiu Dev Root\QiiuTMS\QiiuTMS Release 1\Qiiu TMS Release 1.0\Code\QiiuTmsParts Test App\QiiuTmsParts Test App\obj\Debug\App.g.cs:line 0
       at System.AppDomain._nExecuteAssembly(Assembly assembly, String[ args)
       at System.AppDomain.nExecuteAssembly(Assembly assembly, String[ args)
       at System.Runtime.Hosting.ManifestRunner.Run(Boolean checkAptModel)
       at System.Runtime.Hosting.ManifestRunner.ExecuteAsAssembly()
       at System.Runtime.Hosting.ApplicationActivator.CreateInstance(ActivationContext activationContext, String[ activationCustomData)
       at System.Runtime.Hosting.ApplicationActivator.CreateInstance(ActivationContext activationContext)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssemblyDebugInZone()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException:
       (Null)

Call Stack:

PresentationFramework.dll!System.Windows.Controls.ItemContainerGenerator.System.Windows.Controls.Primitives.IItemContainerGenerator.Remove(System.Windows.Controls.Primitives.GeneratorPosition position, int count) + 0x52f bytes 
  Infragistics3.Windows.v7.1.dll!Infragistics.Windows.Virtualization.RecyclingItemsPanel.CleanupUnusedGeneratedElements() + 0x11e bytes 
  Infragistics3.Windows.v7.1.dll!Infragistics.Windows.Virtualization.RecyclingItemsPanel.a(object A_0 = {System.Windows.Threading.DispatcherTimer}, System.EventArgs A_1 = {System.EventArgs}) + 0x42 bytes 
  WindowsBase.dll!System.Windows.Threading.DispatcherTimer.FireTick(object unused) + 0x2e bytes 
  WindowsBase.dll!System.Windows.Threading.ExceptionWrapper.InternalRealCall(System.Delegate callback = {Method = {System.Object FireTick(System.Object)}}, object args = null, bool isSingleParameter = true) + 0x4a bytes 
  WindowsBase.dll!System.Windows.Threading.ExceptionWrapper.TryCatchWhen(object source = {System.Windows.Threading.Dispatcher}, System.Delegate callback, object args, bool isSingleParameter, System.Delegate catchHandler = null) + 0x3f bytes 
  WindowsBase.dll!System.Windows.Threading.DispatcherOperation.InvokeImpl() + 0x104 bytes 
  WindowsBase.dll!System.Windows.Threading.DispatcherOperation.InvokeInSecurityContext(object state) + 0x28 bytes 
  mscorlib.dll!System.Threading.ExecutionContext.runTryCode(object userData) + 0x43 bytes 
  [Native to Managed Transition] 
  [Managed to Native Transition] 
  mscorlib.dll!System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state) + 0xa7 bytes 
  mscorlib.dll!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state) + 0x92 bytes 
  WindowsBase.dll!System.Windows.Threading.DispatcherOperation.Invoke() + 0x48 bytes 
  WindowsBase.dll!System.Windows.Threading.Dispatcher.ProcessQueue() + 0x102 bytes 
  WindowsBase.dll!System.Windows.Threading.Dispatcher.WndProcHook(System.IntPtr hwnd, int msg, System.IntPtr wParam, System.IntPtr lParam, ref bool handled) + 0x6a bytes 
  WindowsBase.dll!MS.Win32.HwndWrapper.WndProc(System.IntPtr hwnd = 2688078, int msg = 49667, System.IntPtr wParam = 0, System.IntPtr lParam = 0, ref bool handled = false) + 0x87 bytes 
  WindowsBase.dll!MS.Win32.HwndSubclass.DispatcherCallbackOperation(object o) + 0x62 bytes 
  WindowsBase.dll!System.Windows.Threading.ExceptionWrapper.InternalRealCall(System.Delegate callback = {Method = {System.Object DispatcherCallbackOperation(System.Object)}}, object args = {MS.Win32.HwndSubclass.DispatcherOperationCallbackParameter}, bool isSingleParameter = true) + 0x4a bytes 
  WindowsBase.dll!System.Windows.Threading.ExceptionWrapper.TryCatchWhen(object source = {System.Windows.Threading.Dispatcher}, System.Delegate callback, object args, bool isSingleParameter, System.Delegate catchHandler = null) + 0x3f bytes 
  WindowsBase.dll!System.Windows.Threading.Dispatcher.InvokeImpl(System.Windows.Threading.DispatcherPriority priority, System.TimeSpan timeout, System.Delegate method, object args, bool isSingleParameter) + 0x14f bytes 
  WindowsBase.dll!System.Windows.Threading.Dispatcher.Invoke(System.Windows.Threading.DispatcherPriority priority, System.Delegate method, object arg) + 0x3d bytes 
  WindowsBase.dll!MS.Win32.HwndSubclass.SubclassWndProc(System.IntPtr hwnd = 2688078, int msg = 49667, System.IntPtr wParam = 0, System.IntPtr lParam = 0) + 0x1e0 bytes