When using 'Advanced Search', I found the example date format shown in the 'date' fields were fine in IE, but broke out of the page in Firefox. I fixed this by making a small adjustment to the template.

tpl_advanced_search_default.php

Line 58

Change:

<fieldset class="floatingBox forward">

to:

<fieldset style="margin: 0 0 0 8px">

HTH