DNS changer is one of the most dangerous viruses and its rate of spreading among computers is very high. Currently this virus is available in the internet so be alert. Changing the DNS and redirect to fake websites is what this virus can do. As an example, if you try to go www.google.com this virus will direct your request to fake site like www.xxxxxx.com .
You can check, whether your PC infected or not by using this site. http://www.dns-ok.us/
If you got answer “DNS Resolution = GREEN” = your computer is safe
If you got answer “DNS Resolution = RED” = your computer is infected for DNS Changer
If your computer infected take more action to protect your computer according this http://www.dcwg.org/detect
From July 9 2012 onward you can’t access internet if your computer infected this virus. (This is notice from FBI to protect computers from this virus).