PPK (http://www.quirksmode.org/) summarized this problem on his post: Explorer z-index bug (http://www.quirksmode.org/bugreports/archives/2006/01/Explorer_z_index_bug. html): It appears that in Internet Explorer (windows) positioned elements do generate a new stacking context, starting with a z-index value of 0, causing the lime-green box to appear above the yellow box. This is a serious violation of the CSS specifications, causing headages and a lot of misunderstanding of what z-index really does. While crediting Aleksandar Vacić for first reporting this bug, PPK doesn't mention Aleksandar's simple solution. Give the parent a position:relative and z-index:1..( http://www.aplus.co.yu/css/z-pos/)
position:relative; z-index:1 /* More solutions Hedger Wang (http://www.hedgerwow.com/360/bugs/css-select-free.html ) has an ingenious solution to the conflict between z-index on elements and subsequent select elements. He uses an iframe with z-index-1 that sits under the targeted element. I've used this negative z-index on some of the subsequent elements and it is helping. Fixing all of the pages will be a long journey, but at least there is light at the end of the tunnel. */