Thanks for the info, I was able to find the fix for that problem.
Excellent. Thanks for the suggested work around as well.
Experiencing the same issue. I found the PHP that adds the class and removed the space from the class name, but still no dice.
After looking more into it, apparently in IE9 the DOM element of the form container is empty. That means all of the containing divs and input elements are rendering outside of the <form> tag.
Obviously, this messes up any CSS you have declared as form div input{}. Haven’t found a solution yet, but would appreciate any help in finding one.