Javascript Navigation Problem

I am currently building a website that need 2 Javascript Drop-Down Navigation bars.
The reason it needs 2 is that there are so many main links that they just won't fit onto one line.

I have named them both different and each has 2 scripts.
The first scripts are named - mmenu.js and menu_array.js
The other menu scripts are named - mmenu1.js and menu_array1.js

The codes for them on the web page are inside the head and like this:

<SCRIPT language=JavaScript src="scripts/menu_array.js"
type=text/javascript></SCRIPT>

<SCRIPT language=JavaScript src="scripts/mmenu.js"
type=text/javascript></SCRIPT>

<SCRIPT language=JavaScript src="scripts/menu_array1.js"
type=text/javascript></SCRIPT>

<SCRIPT language=JavaScript src="scripts/mmenu1.js"
type=text/javascript></SCRIPT>

When I test them in both I.E & Firefox browsers I get the error message:

Stack Overflow At Line: 487
There is no line 487.

Can anyone tell me what this means and how I can put both menu bars onto the same page?

I have uploaded the script in a ZIP file. If anyone needs to see the codes.

All help much appreciated.

That's not how you use multiple menus on the same page. Did you visit their support page? They have a help page on adding multiple menus on a page (http://www.milonic.com/multiplemenus.php). They even have the Menu Discussion Forum.