Simple selectors based on class names (like $('.myClass')) fail in IE 7 sometimes.

I've got a simple script for switching content who work like this:

$('.myClass2').show();
$('.myClass1').hide();

I figured out that it crached IE 7 only in a particular case, when there are two elements of the same class include in one-another.

Like this.

<div class="myClass1">
     <h2 class="myClass1">SubTitle One</h2>
     (...)
</div>
<div class="myClass2">
     (...)
</div>

I haven't test it more (I've no Windows machine).

Does it fail using more particular selector such as $('div.myClass1')? Does it fail in IE6?

I didn't find any other ticket dealing with this...