InvalidOperationException

MS.Internal.PtsHost.UnsafeNativeMethods.PTS.SecondaryException
  HResult=0x80131500
  Message=The calling thread cannot access this object because a different thread owns it.
  Source=WindowsBase
  StackTrace:
   at System.Windows.Threading.Dispatcher.VerifyAccess()
   at System.Windows.DependencyObject.GetValue(DependencyProperty dp)
   at System.Windows.Documents.Paragraph.get_KeepWithNext()
   at MS.Internal.Text.DynamicPropertyReader.GetKeepWithNext(DependencyObject element)
   at MS.Internal.PtsHost.BaseParagraph.GetParaProperties(FSPAP& fspap, Boolean ignoreElementProps)
   at MS.Internal.PtsHost.ContainerParagraph.GetParaProperties(FSPAP& fspap)
   at MS.Internal.PtsHost.PtsHost.GetParaProperties(IntPtr pfsclient, IntPtr nmp, FSPAP& fspap)

  This exception was originally thrown at this call stack:
    [External Code]

Inner Exception 1:
InvalidOperationException: The calling thread cannot access this object because a different thread owns it.