Unable to sort because the IComparer.Compare() method returns inconsistent results

[glen-84]

styles-x.zip (contains styles-x.xml).

Unhandled Exception: System.ArgumentException: Unable to sort because the IComparer.Compare() method returns inconsistent results. Either a value does not compare equal to itself, or one value repeatedly compared to another value yields different results. IComparer: 'System.Array+FunctorComparer`1[System.Xml.XmlNode]'.
   at System.Collections.Generic.IntrospectiveSortUtilities.ThrowOrIgnoreBadComparer(Object comparer)
   at System.Collections.Generic.ArraySortHelper`1.Sort(T[] keys, Int32 index, Int32 length, IComparer`1 comparer)
   at System.Array.Sort[T](T[] array, Int32 index, Int32 length, IComparer`1 comparer)
   at System.Collections.Generic.List`1.Sort(Comparison`1 comparison)
   at sortxml.Program.SortNodes(XmlNode node)
   at sortxml.Program.SortNodes(XmlNode node)
   at sortxml.Program.Main(String[] arguments)