Jonna talks to computer expert about a virus you should know about called DNSchanger that affects both PCs and Apple computers. How do you know if your computer is infected? Sit down at your computer and type in www.dns-ok.ca You'll either get a green or a red screen. Green means you're in the clear, red means your computer is infected with the DNSchanger. There are many anti-virus vendors, such as Microsoft, that have removal tools that you can download to do the job.