Sometimes it is inconvenient or inappropriate to have the autocomplete feature of IE or FireFox. I found it blocked the custom autocomplete feature I was building for my app. Just add autocomplete="off"
to the form to turn it off:
<form id="formSignOn" autocomplete="off" method="post" runat="server"></form>
In ASP.NET I added it by using the following line:
Me. Form.Attributes.Add("autocomplete", "off")