If you're using a Mac, your Safari browser already has the capability to read and display PDF files. You don't need to install anything else.
If you're getting a black screen instead of a PDF, it may mean that you've installed the Adobe plugin for Acrobat. As of March 2011, that actually breaks Safari's ability to show you PDFs! So you may need to uninstall that. You can do that by deleting this file from your hard drive: