Internet Connection Check

Try This

using System.Net.NetworkInformation;
namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {

        }
        private void button1_Click(object sender, EventArgs e)
        {
            NetworkChange.NetworkAvailabilityChanged += new NetworkAvailabilityChangedEventHandler(NetworkChange_NetworkAvailabilityChanged);
        }
        public void NetworkChange_NetworkAvailabilityChanged(Object sender, NetworkAvailabilityEventArgs e)
        {
            if (e.IsAvailable)
                MessageBox.Show("Connected");
            else
                MessageBox.Show("Disconnected");
        }
    }
}

from msdn :

http://msdn.microsoft.com/en-us/library/aa384702%28VS.85%29.aspx

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