private void Defeat()
    {
        MessageBox.Show("Goodbye");
        this.Close();
    }

An unhandled exception of type 'System.Runtime.InteropServices.ExternalException' occurred in System.Drawing.dll

Additional information: A generic error occurred in GDI+.

private void Defeat()
{
    MessageBox.Show("Goodbye");
    Application.Exit();
}

DialogResult dig = new DialogResult();
dig = MessageBox.Show("Do you want to Clos"Alert!",MessageBoxButtons.YesNo);
if (dig == DialogResult.Yes){
System.Environment.Exit(1);}

private void btnExit_Click(object sender, EventArgs e)
{
  this.Close();  //”this” refers to the form
}