''The dead were coming back to life,'' Alan Van Sprang's soldier wearily intones at the start of George A. Romero's sixth zombie movie, Survival of the Dead. ''We should have been afraid of them, but we weren't.'' That sums up the problem with this Western-inspired film, which plays down the undead plot to concentrate on the feud between two island-dwelling, Irish-accented families. There are some memorable images, including the sight of a beautiful, horse-riding ''dead head.'' But for much of the movie, Van Sprang's zombie fatigue seems to be an echo of Romero's own.
