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Mouse jumping

304 words

I’m slowly getting used to the iBook. The subtle differences such as the keyboard are tricky. I am so used to having the option key next to the enter key (next to the space bar), say. And the order of the option and enter keys is changed on the new keyboard – with the option key being a command key now. Very tricky and very inconvenient as at that location it was perfectly possible to use you ring or middle finger to hold the option key while using the trackpad with your thumb (for copying, say). I can’t do this anymore now, which is sad. It also seems like the Powerbook’s speaker output was much louder and clearer than the iBook’s. Which I obviously don’t appreciate either. But none of these is what I mean to write about.

Rather, I’m asking for help with a really strange problem that I already saw yesterday: My mouse starts jumping around on screen instead of moving smoothly after a while. First I thought this might be related to the USB drive enclosure I’m using but it wasn’t. It seems to be cause by the kernel_task process taking a lot (between 10 and 40 %) of processing power. And this only seems to happen while there is an Airport connection to our flat’s network. In fact, in this situation the network connection can become unstable as well and it even stopped to work yesterday – something that could only be remedied by a restart.

I didn’t find anything helpful on this topic on the internet so far, so if you have any suggestions I’ll be very happy to hear them.

See my followup post for a temporary solution to the problem and rejoice when learning that Apple’s October 2005 Airport software update It seems to resolve the problem.

September 6, 2005, 0:21


Comment by Sören Kuklau: User icon

Seeing as you have an iBook with scrolling trackpad, your kerneltask problem might be related to Leo’s issues, cf. these links (sorted chronologically): http://www.fscklog.com/2005/05/powerbookprozes.html http://www.fscklog.com/2005/05/kerneltaskschu.html http://www.fscklog.com/2005/07/prozessor_fress.html http://www.fscklog.com/2005/08/powerbookkernel.html A bug in Apple’s scrolling trackpad driver, it appears.

September 6, 2005, 2:08

Comment by ssp: User icon

Thanks Sören. I ran across one of those before but this suggests the problem to be more widespread than I thought.

The only strange thing being that I definitely see Airport affecting the whole thing while it’s just the trackpad for everybody else.

September 6, 2005, 10:29

Comment by ssp: User icon

It looks like the problem is related to this discussion at Apple’s support site.

September 6, 2005, 11:05

Comment by Scott: User icon

I have the same problem on ALL of my Macs!

September 7, 2005, 14:31

Comment by ssp: User icon

Interesting… would you mind elaborating a bit?

What kind of computers and OS versions? Do you see the jumpy mouse cursor as well? Does it happen immediately or only after doing some downloading? Does it vanish once Airport is turned off?

Any other things catching your attention?

September 7, 2005, 16:50

Comment by Sören Kuklau: User icon

Well, if you have a USB mouse to attach, you can easily find out if this has to do with your trackpad, by unloading the trackpad driver.

sudo kextunload /System/Library/Extensions/AppleUSBTopCase.kext/Contents/PlugIns/AppleUSBTrackpad.kext/

September 7, 2005, 21:26

Comment by Scott: User icon

It’s really weird. I’m using the latest OS X (10.4.2?). I should say, though, that this only happens with my USB mice, not with my trackpad. But the cursor just starts jumping around the screen—often at seemingly random times. If I’m moving a window, it will drag it all over the screen. Sometimes if I’m just moving the cursor, it’ll drag it into a corner and invoke exposé. If I’m playing Diablo? Oof.

September 8, 2005, 4:37

Comment by ssp: User icon

Sören, I checked that and it didn’t change anything… which might have been clear as the cursor is also jumpy when using the mouse or the graphics tablet.

Scott, that’s strange. I see it on any input device. When do you see that problem? And what’s the load that the kernel_task uses on your system when it is affected?

September 8, 2005, 11:28

Comment by Scott: User icon

That process doesn’t even show up in TOP for me right now, and the problem is happening.

September 8, 2005, 17:04

Comment by ssp: User icon

kernel_task is process number 0, so it’s at the very bottom of the list when you’re running top and might not fit into the window. Just run top -u instead which displays the most busy processes at the top of the list.

Or use Apple’s graphical Activity Monitor to avoid the command line pain…

September 8, 2005, 18:15

Comment by WM: User icon

You can remap your iBook’s keyboard, including changing the Enter key to a modifier key, which isn’t allowed by the Keyboard and Mouse pane of System Preferences. See http://www.snark.de/index.cgi/0007 for details.

I’ve been using this semi-hack for three months now with zero ill effects.

September 10, 2005, 5:18

Comment by ssp: User icon

Thanks for the hint WM… but I think it can’t be used to remap the command key on the right of the space bar to be an option key, which is what I want and miss.

I really like the enter key there (which you can use to quickly dismiss dialogs that come up without needing to move the mouse to the OK button).

September 11, 2005, 1:19

Comment by WM: User icon

I think you could get the command key to be an option key. You wouldn’t edit the same value that I did, obviously, but using the values for the other keys that he gives on the page, I bet you could figure it out.

Changing the 0x37 entry to 0x3a would probably change one of your command keys to an option key, but it might be the left command key, in which case you’d have to guess and figure out which one corresponds to the right command key.

Give it a try, in the spirit of hackery! :-)

September 12, 2005, 7:24

Comment by WM: User icon

Oops, I guess not…on re-reading my own link, he specifically says that there’s no way to separately remap left and right modifier keys.

Well, you could give it a try anyway. :-)

September 12, 2005, 9:41

Comment by Sascha: User icon

mmmh, i ran into the same mouse problem with my new ibook an the mighty mouse, which is connected to the apple standard keyboard. seems to be somehow caused by an airport connection?! i will have a look at these links and check back to this page here later.

so long s

September 18, 2005, 23:17

Comment by sjaddy: User icon

I have the same problem. I have the latest ibook 12”, 1.5gb of ram and a mighty mouse. My system was just doing it—60% of CPU by kernel_task and my cursor was pretty jumpy (mighty mouse). I disabled airport and it instantly went back to normal, kernel_task 2% and the cursor works great.

Is it the airport driver, or something being sent over the network?

October 2, 2005, 22:41

Comment by ssp: User icon

I still have no idea why it is happening. I have filed a bug report with Apple and posted in their support forums but haven’t gotten back helpful information or even a fix.

I suggest that you try to report the problem as well, as a bigger number of people complaining about the problem will make it more likely that Apple consider this problem to be an important one.

October 2, 2005, 22:55

Comment by bjk: User icon

Glad I found this page. I began to wonder if my system was hacked.

I have the jumping cursor problem on a new iBook G4, 1.5 GB RAM (another user mentioned that same amount, so maybe that is part of the problem, since Apple has had large-RAM-problems before.)

One other observation that other might be able to confirm:

Airport performance also drops to less-than-modem speeds. It crawls.

I logged out and in which doesn’t fix the problem. A restart does and things are great for an hour or so, then the problem shows again.

Turning off Airport will immediately fix the jumping cursor. Turning Airport on again will bring the problem back and the slow speed still remains until I restart.

I have also filed a bug report to Apple.

I was so looking forward to the new iBook. But this is a true fun spoiler.

October 7, 2005, 13:06

Comment by ssp: User icon

I guess that filing reports with Apple or even going there and telling their ‘Genius’es if you have any close to yourself is the best we can do now.

It’s just a very annoying problem. And, yes, the speed will be very slow once it has kicked in.

I can reproduce it very easily by doing actions which cause a big number of connections to be established at the same time. Such as reloading all feeds in a feed reader or running a BitTorrent application. So to keep the mouse from jumping it may be wise to try and avoid those uses of the network (which, of course, may not be possible in all situations).

October 7, 2005, 13:37

Comment by bjk: User icon

The problem is also described on MacFixit.com. And indeed the 1.5 GB RAM seem to be part of the problem:


I also got feedback from Apple regarding my bug report: “After further investigation it has been determined that this is a known issue, which is currently being investigated by engineering.”

It’s a standard line, for sure. But it’s the standard line for a recognized bug. That’s good. Hoping for 10.4.3 to fix this or an airport update.

October 12, 2005, 22:45

Comment by bjk: User icon

The bug has already been posted at Macintouch on August 25:

http://www.macintouch.com/newsrecent.shtml#prod.2005.08.25.spss (search for “[Brian Behrend]”

On that same date a thread was started on the Apple discussion boards. But not until this week did posts really take off: http://discussions.info.apple.com/webx?14@539.dZVQaLg2XLY.1@.68b7c1b7

In all reports it turns out that extra RAM seems to trigger the problem.

And Ars Technica has a thread as well: http://episteme.arstechnica.com/groupee/forums?a=tpc&s=50009562&f=8300945231&m=524009175731&r=254006575731#254006575731

All in all the problem seems so wide-spread that Apple better fix this soon before the bad press jumps all over the place.

October 16, 2005, 21:00

Comment by ssp: User icon

I manged to find a temporary remedy for the problem. You might be interested in that.

October 23, 2005, 16:33

Comment by bjk: User icon

Now the new PowerBooks are also affected. I guess that’s a “good” thing, because Apple must do something about this if now - even more users have the problem, - even the more expensive PowerBooks have the problem - especially since PowerBooks are more likely to have lots of RAM installed.

October 28, 2005, 22:26

Comment by bjk: User icon

Here’s the link for the PowerBooks at MacFixit. Read it while it’s still hot. Archived articles require a subscription at MacFixit.


October 28, 2005, 22:27

Comment by bjk: User icon

How is everybody’s experience with the recent updates: 10.4.3. and the Airport update?

I don’t experience the jumping cursor anymore nor the CPU-eating kernel-task.

But the Airport problem still isn’t really fixed: Airport connections are flaky. Sometimes they just hang. Disabling Airport and re-enabling it works usually or at least on second or third try. Sometimes I get an internet connection for a minute or two. But then it stops: No more mail and no web-site will work until I do the Airport on/off trick.

November 8, 2005, 21:32

Comment by Tsoligo: User icon

Soooo glad i found this page… I just got a new powerbook G4 with 2GB of ram and am having this problem…

Looking forward to the solution? Has it been found yet?

November 17, 2005, 17:58

Comment by ssp: User icon

Try running Software Update and installing the October Airport Update. That fixed the problem for everyone I know.

More details for the original problem.

November 17, 2005, 18:10

Comment by senthil: User icon


This is senthil, I got an Issues with the cursor is jumping from one letter to other letter. This problem should be resolve as soon as possible. please give me the solutions


With Regards senthil

June 1, 2006, 11:00

Comment by ssp: User icon

Senthil, the problem I described is not present in current versions of Mac OS X.4. If your system is up to date, I doubt that your problem is related to what is described here.

June 1, 2006, 12:10

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