In ArcMap Version 10 SP3, custom map elements that do not implement IGraphicsComposite and IEnumElement interfaces crash when their properties are accessed.
In order to work with SP3, add the IGraphicsComposite and IEnumElement interfaces to the custom element class: Example implementation: #region IGraphicsComposite Members public IEnumElement get_Graphics(IDisplay Display, object Data) { return this; } #endregion #region IEnumElement Members private int enumIndex = 0; public IElement Next() { if (enumIndex == 0) { enumIndex++; IElement element = new PolygonElementClass(); element.Geometry = m_customElement; return element; } throw new COMException("Iterator End", 1); return null; } public void Reset() { enumIndex = 0; } #endregion