WPF Apps stop responding to touches while mouse continues to work

WPF applications stop responding to the touchscreen (we are using simple button click events) after some period of time (not consistent) but WILL respond to mouse clicks and the non-WPF applications (explorer, etc) continue to respond to touch just fine.

Because the non-WPF applications respond you can likely rule out the touchscreen drivers.

Very similar to this post: http://social.msdn.microsoft.com/Forums/vstudio/en-US/0edc6c2c-f869-4e76-b207-5b2d21078a7f/touch-stop-working

...except that we are not using a SurfaceWindow nor the 'Surface SDK' and we are using an HP Touchsmart computer.  We are running Windows 7 64 bit using .NET 4.5 (Visual Studio 2012).

I wonder if Microsoft melded the SurfaceWindow and Window code together at some point?

Quick Update: We reproduced the issue with our application by disabling the touchscreen in Device Manager and re-enabling it.  WPF application failed to respond to touches afterwards and the rest of the system was still responding to touches.

And here's a simple MainWindow that you can use in a sample app that will demonstrate the issue:

public partial class MainWindow
    {
        public MainWindow()
        {
            InitializeComponent();
            this.Topmost = true; //required to display the problem
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            MessageBox.Show("Click!");
        }
    }

  And the XAML:

<Window x:Class="TestTouchscreenApp.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <Button Content="Button" HorizontalAlignment="Left" Margin="142,62,0,0" VerticalAlignment="Top" Width="178" Height="88" Click="Button_Click"/>

    </Grid>
</Window>