Hey guys thanks for the replies!
I had stripped out all but the lines for the walls, and its a very small house plan with no curved walls at all. I had it all on one layer and purged everything. The UCS was custom to the objects as I rotated the plan to reflect its position to north for the shadows etc.
Ive restored the UCS to the viewport and run AUDIT. Then saved as R14 but still the same result. Ive attached a screenshot showing the overlay of seperate lines clustered along the red axis.
Any ideas, its stumped me 😞