Ghost Viewport

Sometimes a ghost viewport will show up after using the Corridor Section Command. I haven't found a way to remove the viewport via the User Interface. Here is some c#.NET Code that appears to get rid of the bad viewport.

public class FixViewports
{
    [CommandMethod("FixViewports")]
    public static void FixViewportsCommand()
    {
        var doc = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument;
        var db = doc.Database;
        var ed = doc.Editor;

        try
        {
            if (!db.TileMode)
            {
                ed.WriteMessage("Must be in Model Space");
                return;
            }

            using (var tr = db.TransactionManager.StartTransaction())
            {
                var vpTable = db.ViewportTableId.GetObject(OpenMode.ForWrite) as ViewportTable;

                foreach (var vpObjId in vpTable)
                {
                    var vpTblRec = vpObjId.GetObject(OpenMode.ForRead) as ViewportTableRecord;

                    ed.WriteMessage("ViewportName: " + vpTblRec.Name);

                    if (vpTblRec.Name.Equals("*Active", StringComparison.OrdinalIgnoreCase) || 
                        vpTblRec.Name.Equals("Civil 3D Section Editor Viewport Configuration Snapshot", StringComparison.OrdinalIgnoreCase))
                    {
                        ed.WriteMessage("Deleting Viewport: " + vpTblRec.Name);
                        vpTblRec.UpgradeOpen();
                        vpTblRec.Erase();
                    }
                }

                using (var vpRightTblRec = new ViewportTableRecord() { Name = "*Active", LowerLeftCorner = new Point2d(0, 0), UpperRightCorner = new Point2d(0.5, 1) })
                {
                    vpTable.Add(vpRightTblRec);
                    tr.AddNewlyCreatedDBObject(vpRightTblRec, true);
                }

                using (var vpLeftTblRec = new ViewportTableRecord() { Name = "*Active", LowerLeftCorner = new Point2d(0.5, 0), UpperRightCorner = new Point2d(1, 1) })
                {
                    vpTable.Add(vpLeftTblRec);
                    tr.AddNewlyCreatedDBObject(vpLeftTblRec, true);
                }

                vpTable.DowngradeOpen();

                ed.UpdateTiledViewportsFromDatabase();

                tr.Commit();
            }
        }
        catch (System.Exception ex)
        {
            ed.WriteErrorMessage("Error: " + ex.Message);
        }
    }
}