Dock Content script

I have run into a compatibility issue when combining this script with a CSS-only drop-down menu that I am using ( It all works fine in FF2, but in IE7 the menu only works properly once I scroll the page a bit. When the scroll bar is at the top, the drop downs in the menu disappear before I can click on them. Any idea as to why?

Please have a look at to see a minimalist example.