Why is sometimes WebBrowser.Dispose() launching Internet Explorer?

When I do the following (Actually I repeat the same whole code with different web pages):

        Navig开发者_开发问答ator nav;
        nav = new Navigator();
        nav.Browser.Navigate("http://www.amazon.com/gp/search/ref=sr_adv_b/?search-alias=stripbooks&unfiltered=1&field-keywords=&field-author=&field-title=&field-isbn=0471848573+&field-publisher=&node=&field-p_n_condition-type=&field-feature_browse-bin=&field-binding_browse-bin=&field-subject=&field-language=&field-dateop=&field-datemod=&field-dateyear=&sort=relevanceexprank&Adv-Srch-Books-Submit.x=18&Adv-Srch-Books-Submit.y=4");
        while (nav.Browser.ReadyState != WebBrowserReadyState.Complete) Application.DoEvents();
        nav.Dispose();

Navigator is a Form that contains a public WebBrowser and that's it. You can test it yourself and I think the same will happen, but it doesn't happen every single time. You might need to put it in a loop and repeat it a few times for the problem to happen.

Make your Navigator form look like this:

public partial class Navigator : Form {
    private bool done;

    public Navigator() {
        InitializeComponent();
        Browser.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(Browser_DocumentCompleted);
    }
    void Browser_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e) {
        if (e.Url == Browser.Url) done = true;
    }
    public bool Completed {
        get { return done; }
    }
}

And your loop like this:

        Navigator nav;
        nav = new Navigator();
        nav.Browser.Navigate("http://www.amazon.com/gp/search/ref=sr_adv_b/?search-alias=stripbooks&unfiltered=1&field-keywords=&field-author=&field-title=&field-isbn=0471848573+&field-publisher=&node=&field-p_n_condition-type=&field-feature_browse-bin=&field-binding_browse-bin=&field-subject=&field-language=&field-dateop=&field-datemod=&field-dateyear=&sort=relevanceexprank&Adv-Srch-Books-Submit.x=18&Adv-Srch-Books-Submit.y=4"); //        http://msn.com"); //stackoverflow.com/questions/3661536/while-true-application-doevents-doesnt-know-when-the-program-finishes");
        this.Enabled = false;
        while (!nav.Completed) Application.DoEvents();
        this.Enabled = true;
        nav.Dispose();

I had the same problem when I tried to invoke Dispose() function of a WebBrowser in a ThreadPool Queued executing.

I started a Timer in the delegated of Control.Invoke to resolve it. This is my code:

    public delegate void SucceedDelegate();
    // calling by ThreadPool.QueueUserWorkItem(succeed);
    protected void succeed(Object obj){
        Application.OpenForms[0].Invoke(new SucceedDelegate(succeed0));
    }
    private void succeed0()
    {
        Timer timer = new Timer();
        timer.Interval = 1;
        timer.Tick += succeedHandler;
        timer.Start();
    }
    private void succeedHandler(object sender, EventArgs e)
    {
        ((Timer)sender).Stop();
        succeed00();
    }
    private void succeed00()
    {
        //call WebBrowser.Dispose() here
    }

It's ugly, but working well.

Try to add another DoEvents AFTER the loop, just before the nav.Dispose()

            Navigator nav;
            nav = new Navigator();
            nav.Browser.Navigate("http://www.amazon.com/gp/search/ref=sr_adv_b/?search-alias=stripbooks&unfiltered=1&field-keywords=&field-author=&field-title=&field-isbn=0471848573+&field-publisher=&node=&field-p_n_condition-type=&field-feature_browse-bin=&field-binding_browse-bin=&field-subject=&field-language=&field-dateop=&field-datemod=&field-dateyear=&sort=relevanceexprank&Adv-Srch-Books-Submit.x=18&Adv-Srch-Books-Submit.y=4");
            while (nav.Browser.ReadyState != WebBrowserReadyState.Complete) Application.DoEvents();
            Application.DoEvents(); // will avoid launching of IE
            nav.Dispose();