When I enter to my site without using a Google result, I can access without any problems, with and without www.
But, when I access throught the Google results, redirects to Google again.
This is one of my affected sites:
Before Google Search:
http://somesite.com/ – All OK
http://www.somesite.com/ – All OK
Using Google Search
https://www.google.com?q=somesite – First link refirects to Google
After using Google results, if I access to site typing it:
http://somesite.com/ – All OK
http://www.somesite.com/ – Redirects to Google
use Firebug(FireFox Add on) to see what is happening ! It will give you more clarity on what is happening.