Spry Horizontal Menu Problem

I switched to version 2 of the Spry Menubar due to sub-menu problems associated with iPads. Now I am having problems with sub-menus within IE8.  It is not possible to *quickly* scroll down the menu without the sub-menu disappearing.  Here is an example:

http://gerberanalytics.com/tennis/tennis_header_test.php

It works ok with CS6 in the design view, but not on the local test server or on the production server.  Any ideas?

Thanks in advance for your help.