CSS-P Footer problem

This one is doing my nut in…

Against the advice of the board, I’ve pursued with the dynamic tableless layout for my latest site.

Things have been going well, but my footer will not play fair.

The Problem.

I have a #Header and a #Footer on each page.

#Header is set to absolute 0px top 0px left
#Footer is set to 0px bottom 0px left

They work perfectly on load, but the footer moves if i need to scroll… see attached.

How do I get the footer to stay at the botom of the page when scrolling?