In IE, go to Tools>Internet Options>General. Under 'Home Page' select what
you want (any URL you prefer) or 'Blank' - Click Apply and Close/OK and
you'll be set.
Some people report that their PCs need a kind of "refreshment" and they
first establish a blank page for a while before inserting the real page of
their choice in the same place. Maybe this procedure works for you too.
Otherwise use recommended antispy programs.