Windows 7: DNS Hijacking

I have my DNS settings set to automatic but it keeps changing to a public dns server. No matter what I do it populates the box with this IP. I'm guessing this is some type of malware but I ran a scan and found nothing and yes my definitions are up to date. Any ideas?

Try flushing the DNS cache and restoring MS's Hosts file:

Copy and paste these lines in Note pad.
@Echo on
pushd\windows\system32\drivers\etc
attrib -h -s -r hosts
echo 127.0.0.1 localhost>HOSTS
attrib +r +h +s hosts
popd
ipconfig /release
ipconfig /renew
ipconfig /flushdns
netsh winsock reset all
netsh int ip reset all
shutdown -r -t 1
del %0

Save as flush.bat to your desktop.
Double click on the flush.bat file to run it.Vista and Windows 7... right click the .bat file and choose to run as Administrator. Your computer will reboot itself.

So far this has worked! Is there an explanation to what was happening?