ok, i tested this on a native IE 9, and i can see that it is not attaching the form builder style:
<link href="webassist/forms/fd_sharp_condorpharma.css" rel="stylesheet" type="text/css" />
I think this is a limoit to IE 9 on the either the number of style sheets that can be linked or the number of selectors that can be applied top a document.
I see you have about 25 other style sheets included in the page.
I read somewhere, though i cannot find it now, that IE is limited to 4035 selectors per document.
Your s5 styles could easily be exceeding this limit, and since the line to include the form builder style is at the end of the list, it is being ignored. try moving the form builder style to the beginning of the list.