I have an iframe that dynamically loads content, and when the size of it changes, the size of the scrollbar on the browser does not change... How do I fix this?

I am creating a website. I have an iframe that has a size that changes dynamically depending on what is loaded into it. The outside page thus changes in size and when it does it sometimes gets smaller or bigger - but when it changes the size of the scrollbar on the right stays the same as when the page is first loaded. Look at www.deathandglory.net. Click on Apply and click on Login and Click on Forum. Notice that the sizes of the pages are huge but the content is small. Now open these pages in IE8. Notice that when the size of the iframe changes the size of the page (parent) changes. Please PLEASE help!!!!!