The page works fine in IE and Opera. I noticed a problem in FF where the left table moves when you click on the right one.
This comes down to a problem with the <div> elements not having the correct widths.
It's easy to see if you have the Dev Toolbar in FF and outline all Absolutely positioned elements.
I corrected this by setting style.width to "" (which forces a recalculation of it) on the divs. Then the container divs shrank to the correct size.
I'm not sure if this problem is a side effect of some other error (it doesn't pass the
W3C Validator), or what. I doubt it is a problem with the actual script since all the examples on
http://www.walterzorn.com work in FF.