The celebrated jumping mouse of Lion

I haven’t seen any of the major Mac blogs mention it, so I guess it isn’t a widespread problem, but I’ve had the “jumpy mouse” or “jumpy cursor” problem on both my computers since upgrading to Lion.

The problem is simple: you move the pointer on the screen toward a target, and the pointer way overshoots the target, possibly going all the way to one of the corners of the screen. It’s not because you’re snapping the mouse or whipping a finger across the trackpad; you’re using the same motions ingrained by years of habit, but the pointer isn’t behaving the way it’s supposed to.

Here’s a short screen recording I did yesterday on my iMac. I’m using an Apple (née Mighty) Mouse and moving it at about the same speed during all the attempts to resize the window. The sudden jumps in window size aren’t a video artifact from the frame rate or the compression settings, they’re an accurate representation of what goes on when I move the mouse.

As you can see, the jumpiness doesn’t occur with every mouse movement. The inconsistency is almost as frustrating as the jumpiness itself.

I first noticed this on my MacBook Air—which isn’t surprising, since that’s the computer I first upgraded to Lion—while I was using the trackpad. Until I saw some of the aforelinked discussions, I thought my trackpad had gone bad. It was very jumpy a few weeks ago but then seemed to go away, which made me think the update to 10.7.2 had fixed it. I don’t really notice it on the Air anymore.

I didn’t upgrade my iMac to Lion until late last week. At first, I didn’t notice any problems, which sort of reinforced the notion that 10.7.2 was the solution. But on Wednesday and Thursday of this week, I was having terrible trouble controlling the pointer, overshooting almost every button I wanted to click. After doing that screen recording yesterday afternoon, I rebooted, which eliminated the jumpiness for the rest of the day, but it came back this afternoon.

I’ve tried to determine if some background process is the culprit, but haven’t found anything definitive. Time Machine was doing a backup on the iMac this afternoon when the jumpiness returned. I tried to stop the backup to see if that would fix the problem, but Time Machine wouldn’t stop. That’s another bug, but I didn’t feel like running down two bugs at once. Time Machine wasn’t running when I made the screen recording, so the jumpiness can’t be traced exclusively to it.

I logged out and back in again to stop the Time Machine backup. That fixed the jumpy mouse, too, but it’s an unsatisfying solution. I don’t want to have to reboot or log out and in every day.

So the upshot is this:

I hate computers.

7 Responses to “The celebrated jumping mouse of Lion”

  1. Jamie says:

    I hate computers, too.

    My Lion upgrade gripes include: - for one email account, it prompts for a password and won’t take it if I have saved it. I have to delete the keychain password for it to work, until I sleep my laptop. Rinse, repeat. - Safari became a memory leak mess. I spend a lot of time debugging things that need to run in it, and it makes me a little nuts. Seems like the debugger itself is the culprit here, but I haven’t had time to check. My rule is kill it and start over when it uses about half real RAM. - Xcode now officially… Something. It is the only game in town, so there I am. This isn’t just change aversion - lots of devs use multiple screens. Or at least, used to.


  2. Jamie says:

    Oops. Formatting eaten. Oh well.

  3. Ben K says:

    This is not à propos of the point at hand (while I have upgraded one of my computers to Lion I haven’t been using it enough to have noticed with certainty this particular issue), but: Your desktop colour, and the text thereupon (which resembles shell output), suddenly gave me nostalgia for the Amiga CLI.

    I’m relatively new to your blog so I haven’t read enough of your writings yet to be familiar with your background, but perchance were you an Amiga guy back in the day? You seem to exhibit the diversity of interests, wit and insight that I feel inclined to ascribe to such clan. :)


  4. Dr. Drang says:

    Ben, I’m certainly old enough to have used an Amiga, but I never did (I did have a C64, though). The stuff on the Desktop is put there by NerdTool. If you search around a bit on the site, you’ll find several posts about either NerdTool or GeekTool, which I used to use.

  5. Kevin Lipe says:

    I’ve seen the jumping mouse too. I’ve got the last Core 2 Duo 13” MacBook Pro, and it happens from time to time whether I’m using the internal trackpad or my Magic Trackpad.

    I’ve got a laundry list of Lion problems, too:

    • Kernel Panics during shutdown sometimes if my Time Machine drive is connected
    • Until I turned off FileVault (which I didn’t want to do), my machine locked up during every Time Machine backup.
    • I’ve only got one Exchange email account, and I always have to manually take it online in

    The list is longer, but I can’t remember them all. I was hoping the 10.7.x releases would make things more stable, but instead, the normal 10.7.2 update clobbered my machine and I had to install it from an external boot drive via Combo Updater.

  6. David Avraamides says:

    I’ve definitely noticed the jumpy mouse problem, too. But it hasn’t been happening consistently enough to draw any inference with other things that might be causing it. Regarding Time Machine, I stopped using it a long time ago so that isn’t specifically the cause. But maybe any background process that’s stealing cycles could trigger the issue.

  7. James Naylor says:

    Thought I would just drop another ‘me, too’ comment, in the hope it might jog someone’s synapses into recognising what might be causing it.

    I thought it was TimeMachine at first, but then I noticed that it seems to happen more whenever there is any disk activity - so maybe something related to that?

    Although it’s happening now, and I can’t hear any disks chattering, so who knows…?