I'm setting up an older MacBook Pro (it still has the button on the trackpad) and after upgrading it from a fresh install of Snow Leopard to Lion last night my external mouse is not functioning properly.

Left clicks with the mouse are not registered. Right clicking is fine. Moving the mouse around is fine. But left clicks do nothing. I can click with the trackpad button (but this button sticks, which is why an external mouse is required) and that does work.

I have natural scrolling turned off. I have all trackpad gestures turned off. There are no open windows or any dialogs that might be interrupting things. There are no stuck keyboard keys.

One bit of odd is: if I reboot the machine, for a few seconds after a fresh reboot the left click on the external mouse works fines. And then...nothing. Disconnecting and reconnecting the mouse does not fix the problem, even temporarily.

I've tried multiple external mice, wired and wireless, now and it's the same for all of them. All mice are known to be good and function well on my mid-2007 iMac that is also running Lion.


The only thing possibly related in the Console is the repeated message:

IOSurface: Buffer allocation size is zero

And, it appears after one more reboot, things are working okay for me now. I've been using it for ten minutes without the left button on the mouse failing.

  • Are there some old input device drivers that haven't been uninstalled?
    – Lri
    Jul 23, 2012 at 18:11
  • Complete wipe and fresh install of SL followed by a quick SL update to get the App Store and then an immediate update to Lion. Nothing installed on the machine in between any of that. So: no.
    – Ian C.
    Jul 23, 2012 at 18:22
  • Does anything show up in Console? USB event errors, etc?
    – robmathers
    Jul 23, 2012 at 19:14
  • @CanuckSkier updated. Not sure if that message is relevant or not. And...it appears to be working now. Go figure. Thanks for the help everyone!
    – Ian C.
    Jul 23, 2012 at 20:08
  • I don't know for sure, but a quick search suggests that console message is not related. My best guess given a totally clean install would have been a bad .kext or something on the install media, but that's a bit of a shot in the dark. In any event, glad it's working now.
    – robmathers
    Jul 23, 2012 at 20:25

1 Answer 1


The solution was to disable the internal trackpad. The trackpad, one of the older style pads with the separate button along the bottom edge, had a malfunctioning button and that seemed to be at the heart of the problem.

As soon as I disabled the trackpad the mouse would word. And as soon as I re-enabled the trackpad the mouse would cease to work.

For details on how to disable the trackpad see this question and answer.

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