This is the error I got. I'm using Windows 8.1 64bit.
---------------------------
Fatal error
---------------------------
Whoops - fatal error. Press Ctrl-C to copy the contents of this dialog and paste the text into the forums:
The character 'İ' (0x0130) is not available in this SpriteFont. If applicable, adjust the font's start and end CharacterRegions to include this character.
Parametre adı: character
konum: Microsoft.Xna.Framework.Graphics.SpriteFont.GetIndexForCharacter(Char character)
konum: Microsoft.Xna.Framework.Graphics.SpriteFont.InternalMeasure(StringProxy& text)
konum: Microsoft.Xna.Framework.Graphics.SpriteFont.MeasureString(String text)
konum: WindowSystem.Label.get_TextWidth()
konum: WindowSystem.Label.set_Font(SpriteFont value)
konum: WindowSystem.Label.ApplyTextFormat(IHasText component, LabelType type)
konum: WindowSystem.Label.Init(LabelType type)
konum: WindowSystem.Grid.AddEntry(Object key, String entry, Boolean useLineBreaks)
konum: UWGame.ClientSide.Interface.HUD_Windows.HUDHelpPanel.Populate()
konum: UWGame.ClientSide.Interface.HUD_Windows.HUDHelpPanel..ctor()
konum: UWGame.ClientSide.Interface.InGameInterface.PostLoadContent()
konum: UWGame.ClientSide.Client.BeginRun()
konum: UWGame.ClientSide.Screens.LoadingScreen.LoadingQueueMain()
konum: UWGame.ClientSide.Screens.LoadingScreen.Update(GameTime gameTime, Boolean otherScreenHasFocus, Boolean coveredByOtherScreen)
konum: UWGame.Control.Controller.Update(GameTime gameTime)
---------------------------