All browsers have CSS bugs, and IE leads the pack in this area, but that is not the end of the story. Microsoft has seen fit to engineer their browser to deliberately violate the standards in several critical ways. It might just be a mis-guided attempt to "make it simple" for newbie coders, or it might be a cynical ploy to crush the competition, but in any case it creates huge headaches for those of us who desire to employ CSS positioning on our pages.
http://www.positioniseverything.net/ie-primer.html