I had dnschanger trojan and just got rid of it today. It had installed itself on my linksys router, so anytime I removed it using MalwareBytes, it got reinstalled via wireless router. The simple fix was to reset the router with the reset button after removing it from the computer with the above software. This will mean you have to set up a connection again, but it works!
I have AMD 6000+ X2, Vista 64 Ultimate, Biostar MB, 6gb installed, 250 gb hd and 80gb hd, linksys wireless router and Motorola cable modem on comcast.
All else failed to remove it completely until I did this. Also the trojan has been reworked, so the original files that you would look for aren't there. I found it with the registry entries. There are no TDSS files, etc.