Q158: Regeneration says "A creature with this ability is difficult to kill. creatures with regeneration heal damage at a fixed rate, as with fast healing, but they cannot die as long as their regeneration is still functioning (although creatures with regeneration still fall unconscious when their hit points are below 0). Certain attack forms, typically fire and acid, cause a creature’s regeneration to stop functioning on the round following the attack. During this round, the creature does not heal any damage and can die normally."
Does this mean that once I have a creature with regeneration in negative hit points, I have to deal a single point of acid or fire damage to kill it? It's still useful as it has fast healing, but weaker because it can be turned of by fire and acid damage.

And what does "On the round following the attack mean"? Does it mean the creature does not regain hit points at the beginning of its next turn? That appears the most logic way to do it.