HtmlDocument rememberme = this.webBrowser1.Document;
rememberme.GetElementById("remBox").SetAttribute("checked", "false");

HTMLDocumentClass doc = webBrowserControl.Document as mshtml.HTMLDocumentClass;

HTMLInputElement input = doc.all.item("checkboxID", 0) as HTMLInputElement;

input.value ="false";  //Could be 0, not sure...
//could also be input.@checked = false, sorry I haven't actually used this on a checkbox before... one of these should work though

For Each ele As HtmlElement In Me.WebBrowser1.Document.All
        If ele.Name = "accept" Then
            ele.InvokeMember("click")
        End If
Next