Hey there. We LOVE this menu. We are implementing it across site and haven't had ANY problems with it at all until someone drew our attention to the fact that the onclick action is a little buggy in Safari on the Mac. What happens is that it sometimes takes a double-click to expand the drop-down menu but after that first double-click it USUALLY works with a single click but since you double-clicked once, you keep double-clicking and sometimes that means it expands and contracts again. Its just not a perfect user experience. However, less 7% of our users are mac/Safari users and it works fine in Safari 3 Beta on Windows so we can live with it. But still, I'd like to fix it if I can.
Link:
http://www.clarku.edu/departments/biology/
If anyone can offer any guidance, we'd be grateful. Thanks very much.