Hi,

I can reproduce the issue on my side.
After quick investigation I can say that this issue could be a bug in AutoCAD (in both versions - for Mac and for PC): these lines appears in viewport with visual style other than 2D Wireframe when 3D Solids are extremely thin in compare to its area.
Look here:

http://forums.autodesk.com/t5/autocad-2007-2008-2009/quot-ghost-quot-lines-on-thin-3d-solids/td-p/19...

You can try to use SOLPROF workaround or create flatten view of 3D objects with FLATSHOT command, than put the result to Layout.

Maxim