Please Help Us Resolve the problem with FCKeditor

FCKeditor doesn’t display in Internet Explorer at all.
We have 2 identical projects on different hosts. In one of them FCKeditor is displayed in Firefox, other project doesn’t display at all. Before FCKeditor was displayed in the both projects correctly.
We also notice another problem. If we call FCKeditor from domain subfolder, e.g., http://domain/subweb then the editor doesn’t work. But if the editor is in domain root, e.g., http://domain then it displays correctly.
Thanks in advance.