I had this problem -- apparently there's an unpatched Internet Explorer exploit (read
http://antivirus.about.com/cs/adware.../a/qhosts1.htm) that causes your attempts to access search engines like google to be redirected.
Check your /windows/hosts file to see if a bunch of search sites are listed. If they are, clear them out. Also update your antivirus software and run it.
Using a browser other than internet explorer will keep you safe until a patch is released.