XamlParseException was unhandled

Whenever you see an issue like this, it's pretty much guaranteed that something you are relying on to bind to or affect the display has failed (and failed pretty catastrophically). If you add a DispatcherUnhandledException handler into your App class, you should be able to catch the actual exception there, and see what's going wrong.

Update by Tarun:
Check out this link on how to use it. http://www.codeproject.com/Answers/191167/WPF-Application-exits-automatically#answer1[^]

public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
            this.Topmost = true;
>>>HERE>>>>  this.WindowGrid.Children.Add(new Window2(this));

        }
    }

here im gettin the exception...i need jus one correct loophole to fin tis exception..