Impossible to login for users created after system installation

Hi, I have a new ASUS laptop and i just installed Debian stretch , removing completely Windows 10.

I creates three more users for this machine, with gnome users manager, but nobody of them can do a correct login to his desktop.

If i check the xorg log file of user that failes 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)

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