For some reason the first item in that portfolio is getting put into its own container but only in IE9 (IE8 for example has no issues).
First try disabling any active plugins you have running, then view the page in IE. Make sure to refresh your browser 2-3 times and close it completely and open the page again. Just to make sure you aren't viewing a cached version of the page.
Additionally, you can try to re-build that portfolio section in case for some reason its settings were somehow corrupted. It looks like that is one made in the Theme Options>Portfolio. While there, make sure you don't have any portfolio sections that aren't assigned to a specific page. If you do, just hit the red X to remove them and save all changes.