AutoCAD saves only a .bak file not .dwg on exit

[brzeski1]

AutoCAD will only save as a .bak on exit and has to be renamed outside of AutoCAD.
This seemed to have happened on a user's machine and doesn't know what he did to change the setting.

[Opie]

Is it only happening on one machine?

[jaberwok]

Do you have Windows Explorer/My computer set to show all file extensions?
If not, the file might be called "myfile.bak.dwg" but the "dwg" part would not be displayed.

[rkmcswain]

AutoCAD will only save as a .bak on exit and has to be renamed outside of AutoCAD.
This seemed to have happened on a user's machine and doesn't know what he did to change the setting.

What command are you using prior to closing the drawing?
._QSAVE
._SAVE
._SAVEAS