IE positioning problem

I'm designing a new template for this site, which is built on CollegePublisher, and after a lot of frustration with its limitations I'm pretty much okay with the design. There's just one problem left, which only happens in IE as far as I can tell - the section links across the top of the page (News, Opinions etc, which are the #cp_nav div) get shoved to the right of the header image instead of centering directly below it. This is the CSS for the div:

#cp_nav {
position: absolute;
top: 140px;
}

The problem probably has something to do with the div being below everything else in the page's HTML, but unfortunately I don't have control over that bit, hence the absolute positioning. Is there any way around this?

Thanks in advance!