How to handle Windows Security alert dialog box using Watin IE

I am trying to automate a website using W开发者_StackOverflowatIN IE. As the website bans the ip after few request .So I am setting a bool ipbanned =true when ip gets bannned. In that case and i wish to change the IP. The SetProxy method successfully changes the ip adress with port. but on next request I am getting this screen :-

How should I set the username and password in this dialog box from within the program, so that user do not get to see this box and it is set correctly

Below is the code snippet I am using:-

    private void Start_Thread()
    {
        Thread pop = new Thread(populate);
        pop.SetApartmentState(ApartmentState.STA);
        pop.Start();

    }
    bool ipbanned=false;
    private void populate()
    {

            if(ipbanned)
                SetProxy(proxies[0]);

           ///I wish to handle the dialog box here.

            WatiN.Core.Settings.MakeNewIeInstanceVisible = false;
            WatiN.Core.Settings.Instance.AutoMoveMousePointerToTopLeft = false;
            using (IE browser = new IE(URLs.mainurl))
            {
                    ///code
            }
    }
    private void SetProxy(string proxy)
    {
        //code which successfully changes the ip address.

    }

Any help will be deeply appreciated. Thank You :)

You have to use AddDialogHandler to handle the dialog boxes.

You can refer the SO question watin-logondialoghandlers-not-working-correctly-in-windows-7 for code samples