NullReferenceException is thrown while selecting document text before images located in this document are loaded

[DevExpress Support Team: CLONED FROM T219672: Import - RichEditControl hangs while loading an HTML document]
Now I can load this HTML file.
But, then I get the same error again (Object reference not set to an object instance.).
Steps to reproduce it: immediately after the text of the file is shown (but before the image is loaded), select some text with the mouse. It does not occure each time. :-(
StackTrace:
  bei DevExpress.XtraRichEdit.Commands.Internal.ExtendSelectionByRangesCommandBase.set_InitialBox(Box value)
  bei DevExpress.XtraRichEdit.Mouse.ContinueSelectionByRangesMouseHandlerState.ContinueSelection(MouseEventArgs e)
  bei DevExpress.XtraRichEdit.Mouse.ContinueSelectionByCharactersMouseHandlerState.ContinueSelection(MouseEventArgs e)
  bei DevExpress.XtraRichEdit.Mouse.ContinueSelectionByRangesMouseHandlerState.OnMouseMove(MouseEventArgs e)
  bei DevExpress.Utils.MouseHandler.HandleMouseMove(MouseEventArgs e)
  bei DevExpress.Utils.MouseHandler.OnMouseMove(MouseEventArgs e)
  bei DevExpress.Services.Implementation.MouseHandlerService.OnMouseMove(MouseEventArgs e)
  bei DevExpress.XtraRichEdit.Internal.InnerRichEditControl.OnMouseMove(MouseEventArgs e)
  bei DevExpress.XtraRichEdit.RichEditControl.OnMouseMove(MouseEventArgs e)
  bei System.Windows.Forms.Control.WmMouseMove(Message& m)
  bei System.Windows.Forms.Control.WndProc(Message& m)
  bei DevExpress.XtraRichEdit.RichEditControl.WndProc(Message& m)
  bei System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
  bei System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
  bei System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
  bei System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
  bei System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
  bei System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
  bei System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
  bei System.Windows.Forms.Application.Run(ApplicationContext context)
  bei Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.OnRun()
  bei Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.DoApplicationModel()
  bei Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.Run(String[] commandLine)
  bei TestCOM.My.MyApplication.Main(String[] Args) in 17d14f5c-a337-4978-8281-53493378c1071.vb:Zeile 81.
  bei System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
  bei System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
  bei Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
  bei System.Threading.ThreadHelper.ThreadStart_Context(Object state)
  bei System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
  bei System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
  bei System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
  bei System.Threading.ThreadHelper.ThreadStart()