I am using CSS to position my iframe menu to the side of a table that has all my page content. I'm telling it it has 100% for height, but when my content table becomes bigger than the visible window, and you have to scroll down, the iframe does not cover the entire page to the very bottom, just one entire screen's worth of height. How can I make it have a 100% of height of the page not the screen?

Try putting scroll="no" in your body tag. It would be easier if we could see your page. :s