Menu items shouldn't be clickable

Why are the menu items which are category labels, also clickable like menu items when they are pages? Are there anyway to make them not clickable?

On this site Im busy with there are 3 menu items where the labels are categories(with dropdown menus),”Downloads, Join and Members Login”. I don’t want visitors to be able to click on the category label, but rather on one of the items in the dropdown menu. But because the category label is also clickable, some visitors do click on it, which brings up the “Page can not be found” error, This looks unprofessional and confusing. Anybody know how this can be fixed? Thanks!

Here’s a link to the page http://oscasa.com