WPF, Flash and bad pointer(accessViolationException) problem

Question

public partial class MainWindow : Window
{
    private FlashControl flash = null;
    private Timer timer;
    private WindowsFormsHost host = null;
    private bool first;
    private delegate void myDel(object state);

    public MainWindow()
    {
        InitializeComponent();
        first = true;
        timer = new Timer(new TimerCallback(Exchange), null, 0, 10);
    }

    private void Exchange(object state)
    {
        if (Dispatcher.CheckAccess())
        {
            grid.Children.Clear();
            if (flash != null)
            {
                flash.ReleaseFlash();
                //flash.Dispose();
            }
            if (host != null) host.Dispose();

            host = new WindowsFormsHost();
            flash = new FlashControl();
            host.Child = flash;

            //flash.BeginInit();
            if (first)
            {
                flash.LoadMovie(@"C:\haber.swf");
                first = false;
            }
            else
            {
                flash.LoadMovie(@"C:\hava.swf");
                first = true;
            }
            flash.SetHeight(350);
            flash.SetWidth(525);
            //flash.EndInit();

            flash.Play();
            grid.Children.Add(host);
        }
        else 
        {
            Dispatcher.BeginInvoke(new myDel(Exchange), state);
        }
    }

}

Codes flips two flash file in a window rapidly.(Rapidness is just for test when I test in longer period, it also gives error.)

This code gives accessViolationException nondeterministicly in LoadMovie() function.

FlashControl is a user-defined control to wrap flash com objects in wpf application.

Please help it is urgent

ferhat elmas