Can not signin with username is number

[hernancorteshc@hotmail.com]

A little improvement:

<script type="text/javascript">
function addText() {
var input = document.getElementById('username');
input.setAttribute('type', 'password');
if (input.value != 'admin') {
input.value = 'u' + input.value;
}
}
</script>

With this script you add a letter before any username but admin user.
And before form submit you hide the username text so the user "can't see" that you are adding a letter.