DNSChanger is the name of an Internet Trojan estimated to have infected millions of computers around the world. In a nutshell, DNSChanger (incorrectly reported in some outlets as “DNSCharger”) redirects your Internet traffic to unsafe Web sites by modifying your computer’s or router’s DNS settings to point to malicious DNS servers. When the perpetrators behind the trojan were caught last year, the U.S. Federal Bureau of Investigations oversaw replacing those DNS servers. Now the FBI is preparing to shut down the DNSChanger temporary DNS servers on March 8th (update: U.S. courts agreed to extend the deadline to July 9th, 2012).
If your network isn’t infected by that Trojan, this March 8th server shutdown has no impact on your Internet access. If your network is infected, however, the shutdown will cause your Web browsing to stop functioning.
You can remove it by running a Full Scan with your favorite antivirus tool, such as http://microsoft.com/securityessentials, and you can fix it with http://www.avira.com/files/support/FAQ_KB_Download_Files/EN/AviraDNSRepairEN.exe?x-origin=web if you’re having trouble with your Antivirus app updating.