I had a similiar re-routing problem - it turned out to be that a virus file called \"hosts\" in the Windows Help directory was the culprit. I deleted it and everything is fine now. Incidentally, you could try doing an online scan - www.pandasoftware.com has a good one.
I did some investigating into this and learned that a host of people are misusing Browser Helper Objects and Active X controls to reroute IP addresses to sites they want you to go to, basically hijacking your browser. I guess they call it scumware. What\'s worse is that some of them create files in protected directories that Windows will not let you delete so when you restart your computer after cleaning up the corrupted files, they all re-install.
After installing Adaware, CWS Shredder, BHO Demon, Windows Washer and a few other apps designed to fix corrupted BHO\'s it still came back.
Here\'s a resource that covers all of it and what you can do to prevent it: