Whether or not this is possible depending on your quest dialogue setup (I know NWN makes everything uninterruptable by default), it might be a good idea to make some of the quest dialogues (especially starter quest dialogues) interruptible.
If someone goes AFK, or a troll joins and is feeling mean-spirited, it can otherwise lock down the whole turnin. Its probably trivial, ordinarily, though I imagine for a new player it might be frustrating if they can't get directions.
With 50+ people running around there's just bound to mistakes.