Guys i have used the following code to disable an option using jQuery (jquery-1.4.2.min).The disable happens in Firefox , but not in IE.
<SELECT NAME="SCOPE" id="SCOPE">
<OPTION VALUE="G"> Global
<OPTION VALUE="D"> Dynamic
</SELECT>
$("#SCOPE option[value='G']").attr("disabled","disabled");
$("#SCOPE option[value='D']").attr("selected", "selected");
I think i might be wrong but it could be because the select rather than option can be disabled. Since firefox is great and IE sucks, well you can guess why :) you having that problem. Use css to grey out the text of that option.
then on jquery do something like this.
BTW. double check the code as I have not tested this :)