Lightbox and flash problem

Hey people,

Please go here and click in the link “Saint Mary School”:

http://www.greenlubs.com/GL_yo_sembre_un_arbol.html

Navigate through the pics and probably if you are using Firefox 2 or Explorer 7 you´ll notice that the lightbox effect gets “stuck” behind the flash menu…in Safari and Firefox 3 is working nice.

What can I do? I read about z-index which I think is the answer but don´t know how to implement it…any idea?

Thanks.