// ==== STORE CHARACTER ==== //

        public static void StoreCharacter(PlayerBase player)
        {
            using (Stream stream = File.Create(PlayerSettingsFile))
            {
                XmlSerializer ser = new XmlSerializer(player.GetType());
                ser.Serialize(stream, player);
            }
        }


	// ==== LOAD CHARACTER ==== //

        public static PlayerBase LoadGame()
        {

            if (!File.Exists(PlayerSettingsFile))
            {
               return new PlayerBase("No Char Found", EntityGender.Unknown);
            }

            var serializer = new XmlSerializer(typeof(PlayerBase));
            using (Stream reader = File.OpenRead(PlayerSettingsFile))
            {
               return (PlayerBase)serializer.Deserialize(reader);
            }
        }

// ==== PlayerBase class === //

    [XmlInclude(typeof(Berserker))]
    [XmlInclude(typeof(Shaman))]
    public class PlayerBase : IEntity

// === Berserker class === //

 public class Berserker : PlayerBase




// === XML FILE === //

<?xml version="1.0"?>
<Berserker xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Name>Fred</Name>
  <Strength>10</Strength>
  <Dexterity>5</Dexterity>
  <Wisdom>5</Wisdom>
  <Health>25</Health>
  <Gender>Male</Gender>
  <CharacterClass>Berserker</CharacterClass>
</Berserker>


// === ERROR MESSAGE === //

System.InvalidOperationException
  HResult=0x80131509
  Message=There is an error in XML document (2, 2).
  Source=System.Xml
  StackTrace:
   at System.Xml.Serialization.XmlSerializer.Deserialize(XmlReader xmlReader, String encodingStyle, XmlDeserializationEvents events)
   at System.Xml.Serialization.XmlSerializer.Deserialize(Stream stream)
   at RPG.Data.FileManager.LoadGame() in C:\Projects\Role Playing Game\RPG\Data\FileManager.cs:line 55
   at RPG.Frm_GameMenu.Frm_GameMenu_Load(Object sender, EventArgs e) in C:\Projects\Role Playing Game\RPG\FormGameMenu.cs:line 25
   at System.Windows.Forms.Form.OnLoad(EventArgs e)
   at System.Windows.Forms.Form.OnCreateControl()
   at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible)
   at System.Windows.Forms.Control.CreateControl()
   at System.Windows.Forms.Control.WmShowWindow(Message& m)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
   at System.Windows.Forms.Form.WmShowWindow(Message& m)
   at System.Windows.Forms.Form.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

Inner Exception 1:
InvalidOperationException: <Berserker xmlns=''> was not expected.