There seems to be an issue with any shadow-casting light tied to the player. For example, consider the Torch01Shadow item, which I don't think Bethesda uses. It's just a torch with a shadow casting light. When the torch is on the ground, it works okay, but when you equip it the shadows are very flickery and strange. This is without any other lights in the scene. I tried editing the light cast by the candlelight spell to cast shadows and it does the same thing. Any ideas?