This message pops up when we try to "Save As" a dwg opened thru windows previous versions.
We are at this point as the orginal will no long open.

Anyone run into this?
Any ideas on how to find the corrupted object?

I've even tried copying linework into a new drawing...but that's just coping around the corrupted object.



additional info
C3D 2011 64-bit
xreference of the existing topo and linework
feature lines and alignment lines for grading and a new road
profiles for the road alignments
grading objects for some daylighting
a shared existing surface for grading purposes