I just tested this in 2.5.7.1 and i did not find any such behaviour, could you mail me part of the html?
You can try this by putting this code at the end of your body tag
<script>
(function(){
var forms = document.forms || [];
for(var i = 0; i < forms.length; i++){
for(var j = 0; j < forms[i].length; j++){
if(!forms[i][j].readonly != undefined && forms[i][j].type != "hidden" && forms[i][j].disabled != true && forms[i][j].style.display != 'none'){
forms[i][j].focus();
return;
}
}
}
})();
</script>
It is worth a try.