C# HtmlElementCollection "Access is denied" error message on second iteration of loop

I'm using a loop to loop through a search engine page to gather data, and for some reason when I navigate to the second page of results my HtmlElementCollection and Regex.Match functions poop out with this error:

Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))

Here's a copy of my loop code. Can you advise me on how to proceed and what might be causing the issue?

while (((WebBrowser)browser).Document.GetElementById("pg-next")!=null)
{
    //MessageBox.Show("hello"); 
    HtmlElementCollection col = default(HtmlElementCollection);
    col = ((WebBrowser)browser).Document.GetElementsByTagName("a");
    foreach (HtmlElement e in col)
    {
        match = Regex.Match(e.GetAttribute("href").ToString(), @"mysite.com", RegexOptions.IgnoreCase);
        if (match.Success)
        {                           
            this_url = e.GetAttribute("href").ToString();
            //MessageBox.Show(this_url);
            match = Regex.Match(this_url, @"mysite.com", RegexOptions.IgnoreCase);
            this_url = "https://"+match;
            //domorestuff
        } 
        if ((e.GetAttribute("innerHTML").ToString().Contains("Next ")))
        {
            f_perform_operation_on_element (e, "click", null);
            f_sleep(2);
        } 
    }
}

My only current lead, and it could completely wrong, is that the htmlelementcollection is expecting to have the previous pages elements but since I am declaring a brand new collection something is getting messed up. I'm really confused.

Access is denied at :

 match = Regex.Match(e.GetAttribute("href").ToString(), @"mysite.com", RegexOptions.IgnoreCase);

I think it's the e.GetAttribute that is throwing the exception...

two things...first, make sure you are running the application under a full trust account like administrator and second, consider using htmlagilitypack to do things on the html structure:

http://htmlagilitypack.codeplex.com/