Trojan.DNS.Changer

HI I am new to this forum

I have NIS2012 updated to latest version and i run quick scan and full scan and my pc is clean but when i run Malware bytes

he found trojan dns changer and he removes it.i restert and after day or two infection comes back and norton didint get anything.

 

here is link of screeenshot

http://i720.photobucket.com/albums/ww201/DanielZe/Capture.png

 I am runing win7 pro 64-bit