I'd recommend you to remove all absolute positions and z-indexes, except from the logo(which is to overlapped with other elements), and use floats for making your 2 columns in the middle. In that way you don't have to puzzle around the z-index values.
Have a look at some pitfalls of absolute positions at http://www.tyssendesign.com.au/artic...ning-pitfalls/
The Dream is not what you see in sleep; Dream is the thing which doesn't let you sleep. --(Dr. APJ. Abdul Kalam)