No disagreements there, about the older versions of IE at least. IE9+ are pretty darn good at least.. and IE7 as the new 'low' is 1000x better than IE6 as the new low, thankfully.
Anyways, yes, you're right, it's definitely some sort of CSS issue. However, I just tried with IE7 on your home page, and I'm not seeing things like your image above. I see the Login with Facebook button to the right of the red button, not below, the text is different and there's no sidebar. The button looks right to me though on what I see.
Is there a different page we should be looking at? If you want to private message it to me, that's fine if you don't want it public.
Thanks,
Alex