jtsato
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Title</title>
<!--[if lte IE 6]>
<script>
function ativaOptionsDisabled(){
var sels = document.getElementsByTagName('select');
for(var i=0; i < sels.length; i++){
sels[i].onchange= function(){ //pra se mudar pro desabilitado
if(this.options[this.selectedIndex].disabled){
if(this.options.length<=1){
this.selectedIndex = -1;
}else if(this.selectedIndex < this.options.length - 1){
this.selectedIndex++;
}else{
this.selectedIndex--;
}
}
}
if(sels[i].options[sels[i].selectedIndex].disabled){
//se o selecionado atual é desabilitado chamo o onchange
sels[i].onchange();
}
for(var j=0; j < sels[i].options.length; j++){ //colocando o estilo
if(sels[i].options[j].disabled){
sels[i].options[j].style.color = '#CCC';
}
}
}
}
window.attachEvent("onload", ativaOptionsDisabled)
</script>
<![endif]-->
</head>
<body>
<form id='formulario' action='' method='post'>
<table width='100%'>
<tr>
<td><select id="cmbSelecao" name="cmbSelecao">
<option selected>1</option>
<option>2</option>
<option disabled>3</option>
<option>4</option>
<option>5</option>
</select>
</td>
<td>
</td>
</tr>
</table>
<br />
</form>
</body>
</html>
Fonte.: http://forum.imasters.uol.com.br/index.php?showtopic=252386
Testei aqui com esse javascript e funcionou.