After stumbling across this problem recently in IE6 / IE7 there are three things you need to make sure of:
overflow: hidden, is applied to the div that you want to hide the text in
position: relative, is also applied. IE seems to get confused if this isn’t there
a width and height are applied to the div
e.g.
.div { width: 882px;
height: 246px;
overflow: hidden;
position: relative; }