There was a nasty piece of malware a couple of years ago called DNSChanger, which redirected your web browser to advertising sites instead of where you wanted to go. It did this by changing the DNS Server defaults of your Windows machine to remap the domain lookups to their own sites. The rogue DNS servers were identified by the authorities and shut down. Because over half a million machines were infected, the internet authorities ensured that real DNS servers were put into place at the addresses of the rogue servers, so that infected machines would still work normally.
But now, on July 9 2012, these temporary servers will be shut off. Everyone who had been infected and still had the rogue DNS numbers in their Network settings will now get errors when browsing the Web or sending and receiving EMail.
Here is a check to see if your machine is infected. Green bars mean you are OK. Red bars mean that your machine still has the wrong DNS settings. Note, some problems have been reported with some brower versions, if the Canadian or US sites don’t load, visit the European one:
If you are infected or have the wrong IP addresses, check here for removal tools