Just to give you some news, I have change my "bad" MD (Salon) with another one and have just re-install the nvidiad board on it.
After a new boot and config I retrive the black screen with mouse pointer!
I continue my research.
PS: I have no multiple device on the MDs.
Only the core have those (4 Zwave controler !)
I ask to Hari, what I have to do.