All disabled menu items are being displayed under the dashboard's widgets when hovered.
With a little change at line 155 of the file 'menu.css' the problem is solved.
Change from this:
header ul#navigation-menu li.disabled:hover,
}}} To this:
header ul#navigation-menu li.disabled a:hover,
Tested on Firefox 3.6, Chrome 10 and Opera. While I on Linux at the moment, I couldn't test the change on (argh) Microsoft Internet Explorer. Hope this helps, and sorry for the poor English.