Oh boy, yet another IE7 gotcha.
I wrote this piece of jQuery to code to deselect selected option(s) from a select element:
$("[ name = 'selectFieldName' ] option:selected ").attr( 'selected', '' );
Which works fine in Firefox, but then when the QA tested it, it doesn’t work for him and of course he tested in IE7 (which is a good thing).
So googled around a bit, find out this article on jQuery Google Group:
http://groups.google.com/group/jquery-en/browse_thread/thread/af73f2b57473ffb6
So I tweak the code to:
$("[ name = 'selectFieldName' ]").attr('selectedIndex', '-1');
And it works for both FF and IE7.