AutoCAD Civil 3D :: Fatal Error On Surface Smoothing?

I am having an impossible time smoothing a surface created from feature lines in the attached file. I can smooth the service in parts except for the area that I’ve hatched – as soon as I try to smooth that area the drawing freezes or I get a fatal error. Ideally I’d like this surface to smooth to a 3x3 grid.

The things I’ve tried:

-          Exploding the feature lines to 3d polys and recreating them as feature lines before adding them back to the surface.

-          Copying the feature lines to a new drawing and creating a new surface

-          Completely deleting the feature lines and manually re-drawing them from scratch before adding them to a new surface.

-          Adding the feature lines with different supplemental distance and mid-ordinate distances (typically I do 2’ and 0.01’ respectively)

-          Smoothing the surface in sections instead of one global smoothing of the entire surface (it always fails when I get to the hatched area)

-          Smoothing the surface with different grid dimensions.

-          Emailing the drawing to coworkers to see if they can create the surface and smooth it on their computers

-          Combinations of all of the above.

64-bit HP Desktop - HP Z420
Intel Xeon CPU E5-1620 0 @ 3.60 GHz
24GB RAM
AMD Radeon HD 6570
Windows 7 SP1