Only one instance of form in vb.net 2008

// Setup a unique Name for your Application
static Mutex mutex = new Mutex(false, "My_Unique_App_ID");

///
/// The main entry point for the application.
///
[STAThread]
static void Main()
{
    // Delay 3 seconds to be sure that there is no other instance running
    if (!mutex.WaitOne(TimeSpan.FromSeconds(3), false))
    {
        MessageBox.Show("Another instance of this application is already running");
        return;
    }

    try
    {
        // There is no other instances running
        // Launch the application
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);
        Application.Run(new Form1());
    }
    finally
    {
        mutex.ReleaseMutex();
    }
}