No more toolbar or file menus on DS

As I opened a dwg-file contents in a email yesterday, DS will be open without any toolbar. When I do a left-click on the mouse, I've got any choose of toolbar. So I close the windows, and open DS alone : I've got the same problem.  I probire to uninstall, download and install DS : it was always the same. Can anyone help me ?

Best regards,

PEL