ASUS impossible login for other users

Hi, I have a new ASUS F555Q laptop and i just installed Debian testing,
removing completl Windows 10.

It's all ok, but the only thing i cannot do is to log in Gnome session with
other users a part of me.

If i check the xorg log of user that failed login i found these lines at
the end:

'''
[   158.567] (II) RADEON(G0): [DRI2]   VDPAU driver: radeonsi
[   158.567] (EE) RADEON(G0): failed to initialise surface manager
[   158.567] (EE) RADEON(G0): radeon_setup_kernel_mem failed
[   158.567] (EE)
Fatal server error:
[   158.567] (EE) AddScreen/ScreenInit failed for gpu driver 0 -1
[   158.567] (EE)
[   158.567] (EE)
Please consult the The X.Org Foundation support
         at http://wiki.x.org
 for help.
[   158.567] (EE) Please also check the log file at
"/home/francesca/.local/share/xorg/Xorg.0.log" for additional information.
[   158.567] (EE)
[   158.578] (EE) Server terminated with error (1). Closing log file.
'''

Of course i googled these errors but I can't find any solution.

Can anyone help me?

Thanks
Francesco