Why won't CSS justify in Firefox?

My site is in CSS and for some reason the text won’t justify in Firefox. It works in IE, Safari, and Opera. Also, when I change text-align: justify; to text-align: right; it works in all browsers including Firefox. To make it more strange, other CSS site’s show up justified in Firefox. What’s wrong with my code?

Site: www.u-stu.com/index5.html

CSS: www.u-stu.com/core-style.css

I put text-align: justify; in various classes and ids but I think the easiest would be in <p> where it is now.