Probelm with resizing when using 2 menus in a page

[avesta]

I've got 2 set of menus in a single page. Both menus are placed in tables, 1 is horizontal and the other one is vertical.
When I resize the browser window the first menu which is the horizontal one does not replace but the second vertical menu will.
The problem with the horizontal menu goes away when I remove the second menu.
You can see the problem for yourself at:
http://new.sph.tums.ac.ir

Could anyone please help?