title: an unhandled exception of type 'System.ArgumentException' occurred in System.Windows.Forms.dll
body: <p>I'm really a newbie at programming so do excuse me if my knowledge seems really inadequate. I'm doing a C# project for my school and I'm having problems with my homework, thanks</p>
  
  <p>some codes in here:</p>
  
  <pre><code>using System;
  using System.Drawing;
  
  
  private void button1_Click(object sender, EventArgs e)
  {
      child frm2 = new child();
      frm2.ShowDialog();
  
  
      int color = 0;
      int i = 0;
      Random rnd = new Random();
      i = rnd.Next(51);
  
      frm2.BackColor = Color.FromArgb(i*color);
      frm2.ShowDialog();
      if (color == 5)
      {
          color = 0;
      }
  }
  </code></pre>