Problem with drop down menu from Fireworks

[sharkbiteart]

Hi,
I am having a problem with a pulldown menu. I have put up a test site with only the index page here

http://www.sharkbite.ca/clienttempsites/test/wclh-test/

The problem is the pull down works on the first rollover, the does not work until the page is refreshed.

If I take out the Lightbox pop out, then it works fine.

The Firefox Error Console is giving me an error in this line

m.style.visibility = "hidden";

but as I am not a js programmer, I am not sure how to fix it, any help would be VERY much appreciated.

Thanks.