Sidebar wrapping below post area.

I am having a sidebar wrapping problem with my blog. The main page, Archives and the Category pages of the blog are rendering correctly, but when you go to a single post page the sidebar gets moved below the post area.

Here is a link to my main blog http://www.duiprocess.com/blog/

Here is a link to a single blog post page that displays the problem http://www.duiprocess.com/blog/?p=33

The theme I am using is “mtsix”. I did originally have this problem on every page, but after playing around with the padding in the style.css file I was able to fix the problem, but I have not yet been able to fix the problem on the individual post pages.

Any input would be appreciated!