Hola Luis,
Thanks for trying. The following works to undefine the command:
(command "._undefine" ".ACAD_VMTOOLS.3Dorbittransparent")
But as before, if I start the line command, pick first point, then hold the shift key and scroll button, the command still works.
I also tried undefining 3dorbit like this:
(command "._undefine" ".ACAD_VMTOOLS.3Dorbit")
With both commands undefined and the line exercise again, AutoCAD freeze crash.