I've had the same in IE (newest version of 9). No troublemaking plugins on. The weird thing is, at first it would load up fine, but after fully loading the site goes weird. Chrome (17 I believe) and FF 4 are fine.
I've pulled the theme, but still have screenshots.
First load in IE9 which is mostly fine (top ad needs some positioning work) :
Final display after fully loading:
The site gets aligned left, and the whole right sidebar is gone. Header is souped up too.
I have -not- edited the theme at all, so it's a bit strange behaviour I think.
As said, it's not on the site anymore (http://emailblog.eu), but I hope these screens help a bit in fixing the theme for IE 9.