Fn key causes pages to scroll down

Ok, just recently my computer has started scrolling down when I hit the fn key. I am almost positive it didn't do this before. It's very troublesome in word when I want to use the thesaurus and press fn + shift + F7 and the page skips down and doesn't search my highlighted word. Did I hit something and change the function of the fn key? I need to know how to get rid of this.