My npcs don't like dying

[Rian]

I thought it was a problem exclusively with spells at first, and I thought I knew what was up. But now I can't kill npcs. Right before they're about to die their health seems to get stuck in place. And then, blow after blow actually keeps killing the npc, and I get experience for it, but the npcs remains on the map, attacking me.

Does anyone have a clue what might be going on? :x