This is slightly complicated. I have a dxf created by autocad which seems to have been corrupted. It will not open in AutoCAD. However, it opens in QGIS.
I tried selecting the file in QGIS and saving as DXF. however when i try to open it in AutoCAD it cause AutoCAD to crash.
this is a similar question to Exported DXF from QGIS won't open in AutoCAD but it was not adequately answered.