What exactly does "no luck" mean? You change it to a blank page, stop IE, start IE and it's yahoo again?
Then I suspect some extension or add-on. Disable all, in Tools>Manage add-ons and see what happens.
I always use Google as my only Homepage. Suddenly today when I open Internet Explorer the Homepage is Yahoo.
I tried changing it to google through Internet Options but no luck.
I can get to Google by typing in at the btop (is that the URL?) www.google.com.