I'm really wondering that nobody has the problem I have (only with I.E. Explorer 6.0 while with firefox all is o.k.). I've just posted this problem:

When I load whatever page, the box containing the menu is 150px, the same of the other boxes.
When I put the cursor on the menu, the box become larger of about 3px, and there is a little shift of the central part of the screen.

The problem disappears if I change
div#nav-cat li a {display: block; padding: 0.25em 0 0.25em 0.5em; in
div#nav-cat li a {display: block; padding: 0.25em 0 0.25em 0;
but the names of categories are immediately on the left side of the box.

You can see the problem on
http://www.artedicarte.com/catalog

I'm not so expert in css to solve the problem.
Thanks for help. - Giovanni