DatePicker not shows on Firefox 3.5, 3.6

In my applications I am using datepicker application (included in XWiki Enterprise). Strange, but ONLY in Firefox 3.5 and 3.6 (all builds) datepicker small window not shows. Chrome, FF 1.x, 2.x, 3.0 (all builds) - shows. This is not a problem related with datepicker.js - because testing example at http://www.tigretigre.com/datepicker/test.html works at FF 3.5 and 4.6 without any problems. Maybe problem related with scriptaculous, because, for example, content of scriptaculous.js (compared http://www.tigretigre.com and xwiki/resources/js/scriptaculous) is dirrerent at all.