My user was saving a 3D file in 2004 format instead of 2007 format. He was using Map 2008 and was not the original creator of the drawing. Swicthing to save as 2007 in Options got rid of the error.
I too am receiving these errors, I am in Civil 3D, and flipping between the C3D workspace and the 3D Modeling workspace. When I do a copy basepoint of a run of 3D solids of pipes and fittings, I am getting an "AutoCAD Map Messages" dialog box, with repeated messages "An error occurred while saving the drawing." and the Message Details box at the bottom of the window says "Cannot save options in the drawing." and "eHadMultipleReaders"
My Tech support people don't know the cause. Doe anyone understand why this occurs, and why in the world I'd be getting AutoCAD Map messages in Civil 3D anyway, considering I am not working in Map.