Some people remove the pressure clips from the door of the polaroid. that's the only solution i know of...
if i have a pack that is tough to pull, after pulling the first tab, i grip the film end tab with both hands and pull slowly until i get past the point where it will just tear off. but if you can't get the first tab out, then try the mod.
make sure your rollers are clean and don't stick, as well, because the film will jam up in it.