I often downoad files to my desktop like PDF files I want to view (which I'd rather just open in the browser like IE instead of cluttering up my desktop) or just download course files for school. Usually they show up immediately, but sometimes they don't show on the desktop at all. If I open Finder, they will appear, but still not on the desktop. They will randomly show up later.

Anyone have any idea why this happens or what I can do to fix it?