This is a two rail sweep displayed in shaded mode and I get this strange behavior.
ArgoFlex5.3dm.zip (118.5 KB)
Looks like you’ve been messing with the mesh settings.
The render mesh doesn’t fit the surface very well.
Go into File > Settings > Mesh, and set it to Jagged & Faster or Smooth & Slower.
Does that look better?
Just a few links:
http://wiki.mcneel.com/rhino/meshfaq
http://wiki.mcneel.com/rhino/meshfaqdetails
Your settings adjusted:
Yeah, for some reason I’d some ‘custom’ settings left behind in a template I’d modified. There was some tutorial that recommended a custom setting and I entered some time back. Thanks for the help.