Why isn't Internet Explorer respecting any stylesheets?
I could find nothing that allowed me to reproduce this behavior, nor have I ever seen that happen before. I would try opening IE with no add-ons (usually in Start>Accessories>System Tools), and if that does not work, I would consider going to Tools>Internet Options>Advanced>Reset and doing that.
I am not even sure that it is just a browser setting, but the latter option will probably tell you for sure.