CSS Navigation on Menu with Firefox and IE

We have CSS navigation drop down menus on our website. They work the way they are supposed to in Firefox 2.0, but not in IE 7, and not in Firefox 3.0 When you hover over the dropdown and try and go down, they sometimes do not allow you to go down the dropdown to navigate, and sometimes they do. [login to view URL] (any of the sections, Rooms/Rates, Meetings/Events, etc) The other CSS issue is the display of the text on [login to view URL] in IE 6 or less. The text overlaps itself, on the Suggested Itinerary sections of each Itinerary.