For those following the thread;
1) When exporting a drawing that contains images to DWG, the export process creates a DWG file and a linked .PNG file for each image in the drawing, eFileAccessError, which means that something is preventing a file being written,  can occur if:

• You have exported the drawing to DWG, and
• You open the DWG in another application, and
• You try to export the DWG again to the same folder/filename while the DWG is open in the other application.

This is because the other application is holding the DWG and associated PNG files open, locking them against being overwritten. 
The solution is to close the DWG in the other application, or export the second DWG to a different folder.

2) Arcs: if a Group containing Arcs has been Mirrored, in some cases the Arcs can be displaced when exporting to DWG.  A fix is being investigated but in the meantime the workaround is to Ungroup any group that exhibits the issue, prior to exporting the drawing.

Kind regards,
Rob Robinson
Stardraw.com