Hold on Cowboy
This blog post is pretty old. Be careful with the information you find in here. It's likely dead, dying, or wildly inaccurate.
We all know that IE is full of bugs and just plain sucks as a browser… if you didn’t know that you can drop your geek badge off on the way out. So today I ran across the Z-Index bug in IE7.
Sometimes you’ve seen this behavior before: 
The fix is to give the parent of the element with a z-index a slightly higher z-index
<div style="z-index: 1000;">
<div style="z-index: 999;">Content Here</div>
</div>Resources: http://brenelz.com/blog/squish-the-internet-explorer-z-index-bug/