Issues with light following player

[gdarknight]

I'm trying to do "aura" effects for a spell mod, and wanted a light to move in front of the player. The light will appear when the spells is cast, and move in front of the player correctly (i used a marker nif). The proble is the actual rendering of the light...it will disappear sometimes and do the sharp cut-off issue other times. :wallbash:

 

Any ideas how I can fix this? I'm not using HDR if that matters.