X Error: BadDevice, invalid or uninitialized input device 168

Di recente, lanciando diverse applicazioni da linea di comando, ottenevo i seguenti messaggi:

X Error: BadDevice, invalid or uninitialized input device 168
 Major opcode:  148
 Minor opcode:  3
 Resource id:  0x0
Failed to open device
X Error: BadDevice, invalid or uninitialized input device 168
 Major opcode:  148
 Minor opcode:  3
 Resource id:  0x0
Failed to open device

Pare che la causa siano alcune definizioni della tavoletta Wacom sul file /etc/X11/xorg.conf.
Occorre commentare tutte queste definizioni, sia nelle sezioni InputDevice che nella sezione ServerLayout

# Section "InputDevice"
#  Driver        "wacom"
#  Identifier    "stylus"
#  Option        "Device"        "/dev/wacom"          # Change to
#                                                      # /dev/input/event
#                                                      # for USB
#  Option        "Type"          "stylus"
#  Option        "ForceDevice"   "ISDV4"               # Tablet PC ONLY
#EndSection

#Section "InputDevice"
#  Driver        "wacom"
#  Identifier    "eraser"
#  Option        "Device"        "/dev/wacom"          # Change to
#                                                      # /dev/input/event
#                                                      # for USB
#  Option        "Type"          "eraser"
#  Option        "ForceDevice"   "ISDV4"               # Tablet PC ONLY
#EndSection

#Section "InputDevice"
#  Driver        "wacom"
#  Identifier    "cursor"
#  Option        "Device"        "/dev/wacom"          # Change to
#                                                      # /dev/input/event
#                                                      # for USB
#  Option        "Type"          "cursor"
#  Option        "ForceDevice"   "ISDV4"               # Tablet PC ONLY

#EndSection

E ancora:

Section "ServerLayout"
       Identifier      "Default Layout"
       Screen          "Default Screen"
       InputDevice     "Generic Keyboard"
       InputDevice     "Configured Mouse"
#       InputDevice     "stylus" "SendCoreEvents"
#       InputDevice     "cursor" "SendCoreEvents"
#       InputDevice     "eraser" "SendCoreEvents"
EndSection