Positioning a box

I am having trouble positioning a box underneath the horizontal spry drop down
menu bar. I set the positioning top to 0 pixel. the problem is that the box
goes underneath the menu bar rather than below it. How can i fix the issue.
the problem is only on (Iexplorer on windows).
Thanks

.body {
background-color: #E1E1E1;
height: 620px;
width: 900px;
position: relative;
z-index: 1;
margin-right: auto;
margin-left: auto;
margin-top: 0px;
margin-bottom: 0px;
top: 0px;
visibility: inherit;
border-top-color: #E1E1E1;
border-right-color: #E1E1E1;
border-bottom-color: #E1E1E1;
border-left-color: #E1E1E1;
float: none;
}