Javascript Problem Menu + links

Hello. On this site : [login to view URL], we have a top menu made with Javascript. The problem is that when I put my mouse around a parent menu (above for example), submenu aaprears (qhould only appear when the mouse is on the parent menu) AND any link above are not active, espacially on Firefox. For exeample, on home page, we have 4 modules with links and they are not clickable. Thanks for your help Cinthya