Internet Explorer does not work with one theme, does with another

Weird bug... have the xmlns:fb tag in the html tag as described in instructions.
When using one theme, it does not work in IE, but works just fine in Firefox, Chrome, etc.
Using the Zen theme, it works in IE too.
I have no idea what is breaking it within the custom theme.
I put a theme switcher into the sidebar to switch between the two themes... see the weirdness happening at http://dcushing.londondecompression.com
Any ideas?