Crossfire Briefs, like many other debate publications, are delivered as PDF files. A number of programs can be used to create or open PDF files, but Adobe Acrobat and Adobe Reader dominate the market.
Last week, Adobe released a quarterly update that fixes numerous security problems. I strongly encourage everyone to make certain that you have the most recent security release for the version (7/8/9) you are using.
Adobe Reader is available as a free download from Adobe. The latest version is 9.2.
