After installing Ubuntu 12.04 on a macbook pro 6.2, the touchpad and external USB mouse worked perfectly. After rebooting I can't get either touchpad or external USB mouse to work. Sometimes no mouse pointer is visible, but more often I can only move the mouse pointer horizontally five sixths of the way across the display (from the top left).

I have uninstalled mouseemu.

xinput list shows the USB mouse. xinput query-state for the USB mouse shows the following:

ButtonClass
    button[1]=up
    ...
    button[16]=up
ValuatorClass Mode=Relative Proximity=In
    valuator[0]=480
    valuator[1]=2400
    valuator[2]=0
    valuator[3]=3

and re-issuing this command with the pointer at its right hand extreme displays the same except for:

    valuator[0]=1679

So the valuator[0] seems to be the x-coordinate of the pointer and the range of motion 480-1679 is indeed about five sixths of the display width (1440).

valuator[1] is suspiciously large given the display height is 900. Perhaps this is a side-effect of having previously been using a dual monitor (although booting with that monitor connected does not help).

There are other entries listed under xinput list:

1. Virtual core XTEST pointer which seems stuck at position (840,1050).
2. bcm5974 which seems stuck at position (837,6700).

Removing the bcm5974 module using rmmod disables the toucpad as expected but does not fix the USB mouse problem. After adding the module back, it is stuck at position (840,1050) instead of (837,6700).

/etc/X11/xorg.conf was generated by nvidia-settings and contains:

Section "InputDevice"

    # generated from default
    Identifier     "Mouse0"
    Driver         "mouse"
    Option         "Protocol" "auto"
    Option         "Device" "/dev/psaux"
    Option         "ZAxisMapping" "4 5"

although I don't know how plausible these settings are.

Any suggestions?