Once the FBI got around to fixing the problem in 2011, it realized it couldn't simply shut down the rogue servers because infected computers would be left without a functioning DNS, leaving them virtually Internet-less. So it set up temporary servers to give malware-infected Internet users time to fix their computers. And time runs out on Monday, July 9.
You can check to see whether your computer is infected by going to DNS Changer Check-Up which is run by DCWG. If you see a green background your computer is OK. Had your computer been infected with DNS changer malware you would have seen a red background.
(via abc News)