It works fine for me - I placed a WebBowser on my form, added a button, and pasted your line of code into the Click event handler:
void button1_Click(object sender, EventArgs e)
{
webBrowser1.Navigate("http://www.bbc.co.uk/news");
}
Click the button, the page laods, my app is fine.
Check your WebBrowser event handlers - you may have a problem there, or in unrelated code.