Problem with Archive/Category Formatting

I’m having a problem with the formatting of any Archive and Category pages. When I click on, say, my August archives, it shows all of the text aligning to the very left, rather than in the center of the page. Could someone take a look? The problem is only occurring in Internet Explorer and not in Firefox – Firefox must be self-correcting the issue. This is also happening if you click on any of my categories:

Archive example:
http://www.bonbonsinthebath.com/2006/08/

Category example:
http://www.bonbonsinthebath.com/category/facials/

Thanks so much!