Line|Plane Intersection - Stray points

Hay,

I'm using a line plane intersection to create a point for another plane and on about 2% I seem to get a wondering point, The strange thing is if I change the shape of the model the issue seems to disappear.

At first I thought it was an association issue but because of the error of distance it doesn't seem so.

Any one come across this before? If so any work around? 

sorry no files atm as it contains sensitive workings, however a simplified version is possible if needed?