It did that for me too. I can't see why though when looking at the HTML.

    <form name="Cerca" method="get" action="index.php">
    <input type="text" name="sur" size="8">
    <input type="submit" name="s" value="Search">
    </form>

Maybe it is a bug in Chrome.

same tried to autocomplete CC data as well. (was using chrome)