problem with dropdown menu

Hi all,

1st sorry for by bad English

2nd I have a WordPress website http://www.ezbetgerges.com/blog/ runs in Arabic language “RTL Language” and with iNove template
the problem is that when I hover over the menu item called “فيديو مارمرقس” the sub menu cover the main item IN FIREFOX ONLY while it works right in other browsers

and there are 2 pictures (1st is the normal view without hovering – and the 2nd is while hovering)

http://www.ezbetgerges.com/blog/wp-content/themes/inove/img/no-problem.jpg

http://www.ezbetgerges.com/blog/wp-content/themes/inove/img/problem.jpg

I’ll be so thankful if you help me guys .. coz I can’t find it out !