I'm pretty new to CSS, though I've done a bit of Flash, so I'm not sure exactly how to phrase this question and haven't been able to find a solution.
I'm designing on a mac. The layout looks fine in Safari, Firefox, and Opera, but in Explorer 5.2 on mac and 5, 5.5, and 6 on Windows, the sidebar begins below the end of the main content.
I've tried a number of solutions, including rebuilding the CSS and HTML from the start, adding in pieces until the problem appears, but when I backtrack it remains, so I have no idea what is causing it.
Can anyone help me on this, I'm sure it's a very simple solution but I have no idea.
The site is
the css is