Question

The above code works well in all browsers except in IE8 where it only works in compatibility-mode. I removed all the markup inside the DIVs, there where huge TABLEs.
In IE8 when I check the checkbox(‘rf’), it is suposed to show only two DIVS(#frmRF and #frmAntenas), but it’s also showing the DIV(#frmTX), if you think the markup is not ok, it was generated by Zend_Form, I’d like to not have a hidden for each checkbox I create.

 <script>
$('input[name="rf"]').change(function(){
    if($(this).is(':checked')){
        $("#frmRF").show();
        $("#frmAntenas").slideDown();
    }else{
        $("#frmRF").slideUp('slow');
        if(!$('input[name="tx"]').is(':checked'))
            $("#frmAntenas").slideUp('slow');
    }
});
</script>

<TABLE>
<TR>
    <TD>
        <INPUT value=0 type=hidden name=rf ><INPUT id=rf value=1 type=checkbox name=rf> <FONT class=legenda>RF</FONT>
    </TD>
</TR>
</TABLE>

<div id=frmAntenas style="display:none;">
<fieldset> 
<legend>Especificações Técnicas da Solicitante:</legend>

    <div style='margin-top: 10px' id='frmRF' style="display:none;">

    </div>

    <div style='margin-top: 10px' id='frmTX' style="display:none;">

    </div>

</fieldset> 
</div>

Answer 1

First of all sorry, I have no clue how to comment, don’t see any button for it.
I think I’ve had a similar problem for a while and I have turned off slidedown for IE. I think this is just something IE doesn’t handle too well..
So I think you should try this and see if it works:

   <script>
    $('input[name="rf"]').change(function(){
    var speed  = $.browser.msie ? 0 : "slow";
        if($(this).is(':checked')){
            $("#frmRF").show();
            $("#frmAntenas").show(speed);
        }else{
            $("#frmRF").hide(speed);
            if(!$('input[name="tx"]').is(':checked'))
                $("#frmAntenas").hide(speed);
        }
    });
    </script>

I believe slideup/down does the same as showing and hiding stuff (“slow”), so i adjusted that.

Lauw

Edit:

It worked for me when I put it online and changed your HTML to the following:

<div id=frmAntenas style="display:none;">
<fieldset> 
<legend>Especificações Técnicas da Solicitante:</legend>

    <div id='frmRF' style="display:none; margin-top: 10px">

    </div>

    <div id='frmTX' style="display:none; margin-top: 10px">

    </div>

</fieldset> 
</div>

The thing here is that you were defining ‘style’ twice on the div, so it did not catch on to the display:none;
Editted answer after commenting.
Hope this solves it,

Lauw