It sounds like you have an unhandled exception going on there. In your App.xaml.cs, add an override for OnStartup and add the following line into it:
DispatcherUnhandledException += app_DispatcherUnhandledException;
Then add in the app_DispatcherUnhandledException method:
static void app_DispatcherUnhandledException(object sender, System.Windows.Threading.DispatcherUnhandledExceptionEventArgs e)
{
}
Also, check your Output window in Visual Studio. This is an excellent location for identifying issues that cause crashes, invalid bindings, etc.