I agree Rick, but unfortunately, SU just does not tolerate models that are far from the origin.
I use this trick to help though. In my CAD plan, I draw a triangle (or any object really), rather large, to the bottom left of my CAD model. And when I export things from my CAD file, I always use the wblock command. So I select all contours, AND my triangle, and then wblock it out to a separate file. Then I import that into SU, and I force it to ignore the model origin. What this does is it then lines up that object I drew on the SU origin. And everything I export from CAD from then on, I just export that trianlge shape alone with it and it wil always import right where I want it. Or if ever these is a problem, I always have that triangle that gets imported and I can then rotate and scale the new import so it fits perfectly with the existing.
Sounds harder than it is and so far it has worked perfectly for me. And I think it might help with your bizarre linework.
Chris