1) Created simple dwg using acad2005. Saved in acad2004 format.
Drawing1.dwg 26.94K
0 downloads 2) copied file
Drawing1 - Copy.dwg 26.94K
0 downloads 3) opened copy in nanoCAD 4.5 & made simple edit & saved with different name in acad2004 format.
Drawing1 - Copy nanoCAD.dwg 9.67K
0 downloads 4) copied drawing and opened in acad2005.
Drawing1 - Copy nanoCAD - Copy.dwg 9.67K
0 downloads 5) tried to save (w/o any edits) and I get ACAD2005 message FATAL ERROR: Unhanded Access Violation Reading 0x43f6938 Exception at 651792f6h.