Comment 3 for bug 713556

If it helps, here is the relevant part of my xorg.0.log

[ 20.692] (II) config/udev: Adding input device A4Tech USB Full Speed (/dev/input/event4)
[ 20.692] (**) A4Tech USB Full Speed: Applying InputClass "evdev pointer catchall"
[ 20.692] (**) A4Tech USB Full Speed: always reports core events
[ 20.692] (**) A4Tech USB Full Speed: Device: "/dev/input/event4"
[ 20.700] (II) A4Tech USB Full Speed: Found 20 mouse buttons
[ 20.700] (II) A4Tech USB Full Speed: Found scroll wheel(s)
[ 20.700] (II) A4Tech USB Full Speed: Found relative axes
[ 20.700] (II) A4Tech USB Full Speed: Found x and y relative axes
[ 20.700] (II) A4Tech USB Full Speed: Configuring as mouse
[ 20.700] (**) A4Tech USB Full Speed: YAxisMapping: buttons 4 and 5
[ 20.700] (**) A4Tech USB Full Speed: EmulateWheelButton: 4, EmulateWheelInertia: 10, EmulateWheelTimeout: 200
[ 20.700] (II) XINPUT: Adding extended input device "A4Tech USB Full Speed" (type: MOUSE)
[ 20.700] (II) A4Tech USB Full Speed: initialized for relative axes.
[ 20.700] (II) config/udev: Adding input device A4Tech USB Full Speed (/dev/input/mouse0)
[ 20.700] (II) No input driver/identifier specified (ignoring)
[ 20.701] (II) config/udev: Adding input device A4Tech USB Full Speed (/dev/input/event5)
[ 20.701] (**) A4Tech USB Full Speed: Applying InputClass "evdev keyboard catchall"
[ 20.701] (**) A4Tech USB Full Speed: always reports core events
[ 20.701] (**) A4Tech USB Full Speed: Device: "/dev/input/event5"
[ 20.735] (II) A4Tech USB Full Speed: Found 1 mouse buttons
[ 20.735] (II) A4Tech USB Full Speed: Found scroll wheel(s)
[ 20.735] (II) A4Tech USB Full Speed: Found relative axes
[ 20.735] (II) A4Tech USB Full Speed: Found absolute axes
[ 20.735] (II) A4Tech USB Full Speed: Found x and y absolute axes
[ 20.735] (II) A4Tech USB Full Speed: Found keys
[ 20.735] (II) A4Tech USB Full Speed: Configuring as mouse
[ 20.735] (II) A4Tech USB Full Speed: Configuring as keyboard
[ 20.735] (**) A4Tech USB Full Speed: YAxisMapping: buttons 4 and 5
[ 20.735] (**) A4Tech USB Full Speed: EmulateWheelButton: 4, EmulateWheelInertia: 10, EmulateWheelTimeout: 200
[ 20.735] (II) XINPUT: Adding extended input device "A4Tech USB Full Speed" (type: KEYBOARD)
[ 20.735] (**) Option "xkb_rules" "evdev"
[ 20.735] (**) Option "xkb_model" "evdev"
[ 20.735] (**) Option "xkb_layout" "gb"
[ 20.735] (EE) A4Tech USB Full Speed: failed to initialize for relative axes.
[ 20.735] (WW) Device 'A4Tech USB Full Speed' has 37 axes, only using first 36.
[ 20.735] (II) A4Tech USB Full Speed: initialized for absolute axes.
[ 20.736] (II) config/udev: Adding input device A4Tech USB Full Speed (/dev/input/js0)

I think this a udev configuration problem.