I also have the same problem with this. All of my sub-menus are correct width in IE but not in FF and Chrome.
I can't find any problem in CSS. I am very new for CSS.
1. I created vertical dhtml menu and I set width 350 and height 550 in html file then I put to submenu item>General>HTML.
All the width of the submen are too big than i set in the Chrome and FF browsers. IE is ok.
2. Other thing is can I set the fixed position for X and Y for submen item? I want to put in one fixed postion like http://www.porsche.com/usa/
I don't have the link as i m running on local host.
Please help asap!! thank so much.