I currently run Norton Anti-Virus 2003. I hear that it is one of the most popular virus protection software. It has automatically detected and removed some viruses from my computer. Whenever I download a file, I right click on it and scan it with Norton Anti-virus. I once did this with one file, and I got a report that said their was no infection. I decided to run the file and all of a sudden, Norton had said it detected and removed a virus from my computer! I assumed this file must have contained a virus, but why didn't Norton detect it when I scanned the file before I ran it? Is Norton really the best anti-virus software, or is there anything better? Can one file by itself be a virus, or are always viruses put in a regular good file, or both?