Previous 1 2 3 4 5 Next 192 Replies Latest reply: Nov 11, 2008 5:12 PM by Lokesh Nara Go to original post
  • jkottke Level 1 Level 1
    Just to add to the discussion, I've been experiencing this problem with my 15" 1.67 GHz Powerbook as well. Cmd-tab and poof...nothing works except for the mouse. (Two other people in my office have this problem as well, one has a 17" MBP and the other a black MB.) It happens every few weeks or so (first instance occurred 2-3 weeks after I bought it), but has happened 3 times in the last two days, prompting me to try and track down the problem, which led me here.

    I bought this computer about 3-4 weeks before the MacBook Pros came out (mid-Dec), so it's not a chip problem but it could be another piece of hardware that they just recently started putting in a graphics card maybe?
  • Ethanee Level 2 Level 2
    Like Ian, I am starting to think this could be a bug in the graphics library, it looks like an exception occurred that wasn't handled very well. I don't know how reliable the hardware test is, but I think that should eliminate problems with the graphics card. Perhaps the next step is to find some way of reliably replicating it, for instance one might write a simple program that keeps keying in cmd-tab, cycling through all the open windows. I don't know how or if that's possible, but if so, hopefully that will cause the bug to appear much faster. Then someone can bring it to Apple and duplicate the problem before them.

    Btw, I guess there must have been people who submitted bug reports? Is that via the same feedback channel at
  • Erin Dalzell Level 1 Level 1
    Just for sh*ts and giggles, I wonder what happens if you use a different cmd-tab switching program, like Proteron's LiteSwitchX ( I have been using it for years with no problems and I am currently running it on my white MB running 10.4.8.
  • Ian Searle Level 1 Level 1
    I have tried not using cmd-tab. Though, I failed at not using it at all (old habits die hard). I was able to substantially reduce my usage of cmd-tab and still ran into the problem.

    I'll give liteswitchx a try.

  • L.E. Kun Level 1 Level 1
    Just to add: this happens on my MacBook CD. It started happening frequently and I reinstalled and then it didn't happen for a while. Now it happens infrequently.

    I echo much of what has been said: Often happens on cmd-tab switch, but other than that, no other common denominators. I don't have any haxies or low level system software (like a fan control program installed). I don't even have CoreDuoTemp installed.

    I had heard it was a hard drive failure. That your hard drive is parked and when you command-tab it goes to rev up and doesn't – hence the freeze except the mouse.

    To be clear, for me everything is frozen on screen except the mouse.
  • Erin Dalzell Level 1 Level 1
    LiteSwitchX allows one to use cmd-tab. I too, am addicted to it.
  • cameronfactor Level 1 Level 1
    I've had this same problem on and off with different models since the G4. I posted about it a year and a half ago:

    It hasn't happened on every rev of the OS or every model I've had, but I have had the problem occur on multiple machines (and the comments show that many other people have as well).
  • Ian Searle Level 1 Level 1
    Wow, thanks for posting that link. I had that problem on an older 15" Powerbook Ti model. But, I don't think this is the problem we are discussing herein. That is, when the keyboard freezes, you can still use the mouse to quit applications and logout. But, with this freeze, the mouse moves, but clicking and moving operations don't do anything. Also, I've tried cmd-opt-esc (force-quit) when the freeze happens and nothing.

    But, I'm sure glad to read your post on the keyboard freeze. If that ever happens, I'll know how to recover without logging out or rebooting. Thanks!

  • Nick2005 Level 1 Level 1
    Like some others who responded to your post, I'm experiencing the same problem. I've had the system (MacBook Pro, 17", C2D) for almost a week, and during that time, I've had 5 of these lockups/hangs.

    Just to reiterate the details:

    When the machine "hangs", I can move the mouse, but nothing responds when I click on it.

    When listening to music with iTunes, the music continues even while the machine is "hung".

    While the machine is "hung", I can SSH into it (suggested by another poster). Furthermore, I can then "kill" the WindowServer, which causes the machine to return to the login window (suggested by that same poster). Once at the login screen, I can log in and continue to use the machine without restarting.

    In an attempt to fix the problem, I've
    - reformatted the system (with the "zero" option),
    - reset the PMU, and
    - reset the System Management Controller.
    These steps haven't fixed the problem.

    In an attempt to diagnose the problem, I've
    - run Apple's diagnostics several times,
    - run Disk Utility to repair permission/disk more times than I can count, and
    - run the full suite of tests from TechTool Pro.
    Nothing turns up a hardware problem.

    So now the question becomes:
    How do we get Apple's attention re: this issue?

    I called the other day and spoke with a technician -- Kevin. He told me that "Mac OS X has no bugs in the general operating system." I laughed. I'm not saying that this problem is necessarily a software bug, but his claim is rediculous. With that kind of attitude, how do the OS developers ever receive bug reports? After speaking with a supervisor --Harley-- I received a similarly rediculous response.

    Maybe posting these details in this forum will help? We'll see.

    MacBook Pro 17" (C2D)   Mac OS X (10.4.8)  
  • George Haritonidis Level 1 Level 1
    Excellent post Nick, and thanks for posting your findings.

    The killing of windowserver is an interesting point, I guess this wouldn't 'harm' the machine as much as turning the machine off and on again without it being able to shut down properly.

    I am having exactly the same issue and symptoms as you -- this is a little bit of relief for me, as I know now that it is an issue with these machines. Also it must be something fundamental, as both the 15" and 17" MBP and one occurance of it happening on a Core Duo (I think? earlier in this thread) has occurred.

    Are you command-tabbing into an app when the machine hangs? Either when you first initiate the keyboard command, or when you let the keys go? What video card is in your MBP? There are some clues that this hanging is due to CoreGraphics, however whether it's hardware or software issues that are causing this is still unknown, unfortunately.
  • Nick2005 Level 1 Level 1
    The problem occurred
    (a) three times while importing my music library (~3500 songs) into iTunes via its "Add to Library..." option in the "File" menu,
    (b) once immediately after pressing command-space to use Spotlight (the search box was fading in when it hung), and
    (c) once moments after starting my system and signing in (I don't recall the particular task).

    I seemed to be able to repeat the problem during the iTunes import. (To finally import my whole library, I imported batches of 500 or so songs, because it hung every time I tried my whole collection.) At that time, I had never tried SSHing to the "hung" machine...

    For the fun of it, here's what I'll do:
    (a) remove all of the songs from my iTunes library and
    (b) attempt to import them again in one big batch.
    It seems like a long shot (I wonder whether it's a different problem?), but it's worth a try. If it hangs, I'll try SSHing to the machine and if that works killing the WindowServer.

    I'll post my results as soon as I have them.

    To answer your question, my graphics card is the ATI Mobility Radeon X1600 (256 MB).

    MacBook Pro 17" (C2D)   Mac OS X (10.4.8)  
  • Nick2005 Level 1 Level 1
    It looks like I'm experiencing two types of freezing (aren't I lucky).

    The iTunes locking is reproducible (I just reproduced it for the fourth time) but different than the other two instances of locking.

    For the iTunes locking, my HD essentially stops. I can move the cursor and select programs on the dock. The selected programs bounce but refuse to load; apparently nothing can access the HD (i.e., no clicking). I tried SSHing to the machine but it wouldn't work. Interestingly enough, I could still ping the machine (which makes sense, since it shouldn't require any HD access).

    For the iTunes locking, I will bring my computer into an authorized service centre, reproduce the problem, and probably get the HD replaced.

    We still have the apparently separate issue of non-HD related hanging...

    MacBook Pro 17" (C2D)   Mac OS X (10.4.8)  
  • George Haritonidis Level 1 Level 1
    Okay, this has just occurred again.

    This time I only had about 4-5 apps open, and I was command-tabbing into when the machine locked up. My mouse pointer was still the link 'glove' when you hover your pointer over a hyperlink in Safari. I also had my backlit on, I obviously couldn't adjust the brightness or to turn it off through the keyboard (and obviously through the OS).

    I cold started, and then started to examine if there are any extra clues that I could pick up this time. I may have come across something though, but I am not sure if it is coincidence or not.

    I usually have my MacBook Pro on my desk sitting on an iCurve and hooked up to a 17" Hyundai flat panel display and use an Apple wireless keyboard and wireless mouse to interact with the computer. Sometimes however I like to go portable, so I disconnect my Hyundai LCD and yank all the other cables out and move around with the machine.

    I have timestamps of that CoreGraphics error that correlate to a similar time that I'm guessing occurred when I removed the DVI connection to my LCD secondary display -- ie. my theory is, yank out the secondary display from the machine, and maybe these errors may appear in system.log. Do a command-tab after that (or maybe some time after those errors display) and the machine hangs.

    This is a theory, I haven't actually tried it yet. I'll give it a shot after I have written this post, I wanted to post my thoughts and speculation here first.

    I guess the question I can ask the other people who are experiencing this problem is -- do any of you use a secondary display? Either have it hooked to a TV via composite/S-Video, VGA or DVI connection to a secondary monitor and use desktop spanning. This is how my set up is, and it would be very interesting if all of you (or even some) have a similar set up to mine.

    So here goes -- going to try and force this hang to occur again. See you guys on the other side.

    15" MacBook Pro Core 2 Duo 2.16GHz, 15" PowerBook G4 1.67GHz   Mac OS X (10.4.8)  
  • George Haritonidis Level 1 Level 1
    OK so I plugged in my external monitor into my DVI port with open, and as soon as the displays refreshed, I got the CoreGraphics buffer errors instantly show up in system.log.

    I started repeatedly command-tabbing from Finder to and back again. After 2 minutes of doing this, the machine hung with the bezel still on the screen.

    I guess I have found out how these errors occurred, and they seem to have a strong correlation to CoreGraphics and some buffer overflow. I don't know why these occur though.

    Could anyone who doesn't mind using their machine as a guinea pig try the following experiment on their own machines so that we know that this isn't a one-off? Then perhaps we could contact Apple through a bug reporting site or something and hopefully get their attention.

    I never got this problem with my PowerBook by the way, I used to be able to connect and disconnect my screen at whim (desktop spanning mode) without any ill effects. Is this supposed to be different with the MacBook Pro, or is it suggested that this is a wrong thing to do from Apple?
  • George Haritonidis Level 1 Level 1
    Sorry, my post may seem a little muddled -- I was quite excited when I found out how this is happening.

    "I guess I have found out how these errors occurred, and they seem to have a strong correlation to CoreGraphics and some buffer overflow."

    What I meant was that there seems to be a strong correlation between desktop spanning (plugging in and out a second monitor) and CoreGraphics buffer errors.

    Then these errors somehow reach a saturation point during command-tabbing that will lock a machine up.

    I'm hoping that other people that reported the same symptoms are using secondary monitors in desktop spanning mode. If so, then we have found the root of our problem.

    -- George
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