11 Replies Latest reply: Apr 18, 2010 7:46 AM by DrGreen
erahi Level 1 Level 1 (0 points)
For the past few months i've been having issues with my imac 2.66Ghz 24 inch. I'd say almost half the time when i put my imac to sleep it doesnt wake up no matter how many keys i press and it just stays stuck on a black screen. I know that when you put the computer to sleep you hear absolutely no noise however in this case i hear a slight fan noise despite it 'sleeping'. When this happens i always have to use the on/off button to do a reset. What seems to be the issue here??

I posted this several weeks ago on these forums and the responder suggested that i reset the PRAM and SMC and after doing this, it seemed that the problem was solved as i had no issue for a couple of weeks, however the issue has returned and im not sure what to do now. Was thinking maybe i could take it to apple since its under warranty still, but before i do i might have one more crack at it and see if i can fix this. Any other suggestions?

iMac 24-inch 2.66GHz, Mac OS X (10.6.2)
  • farnsfield Level 1 Level 1 (0 points)
    I have a new 27" i7 iMac and I've had this problem since I've had it. I have been playing around with the energy saver preferences panel to see if it makes any difference.
    When I have it on the default setting which is computer sleep and display sleep set at 10 minutes also with 'put hard disks to sleep when possible' and 'wake for network access' both checked, it will not wake at all, I've pressed every key on the keyboard and clicked the mouse button and tried pressing the power button on the back of the imac. I also tried attaching a wired keyboard in case it was a bluetooth problem but the only option is to hold in the power button and shut it down.

    The last 3 days I have set the computer sleep and display sleep to 'never' and unchecked the 'put hard disks to sleep when possible' and 'wake for network access' boxes and found that this has worked quite well after I've put it to sleep and only once did it fail to wake, this may be to do with an application that I had open but I'll need to test this out as I can't remember what was open when it failed to wake!
  • codyk23 Level 1 Level 1 (0 points)
    Same thing has been happening to me as well. I've got the new 27" iMac. When it goes to sleep, I can tell it's not completely off cause the back of the system is still warm, but it doesn't respond to the keyboard or mouse, just a black screen. It freaked me out the first time, cause I just converted over from PC, and I thought I had a dead iMac on my hands. I'm used to blue screens (BSOD), but not black. And cause the Mac has no power lights to indicate on or off, how can anyone tell?
    However, just pressing the power button to reset doesn't work for me. I have to force it with a Control-Command-Power button combination to get it to shutdown/restart.
    I don't know what the problem/solution is, but now I shut down my Mac instead of letting it go to sleep for long periods of time.
    I'd be interested to know what the official reason for this problem is from Apple.
  • straightshooter Level 1 Level 1 (5 points)
    I've been having a similar problem with my 24" iMac. On waking (by moving the Logitech trackball, or pressing the space bar) I occasionally get a black screen (sometimes following a very brief screen display flicker). It sounds like the machine is awake but I just get a black screen, as if in display sleep - but no amount of key pressing or "mouse" moving seems to wake it fully. My solution so far has been to press the power button briefly (to put it to sleep again) waiting for the internal hard drive to spin down and the light to go off on my external HDD, then reawakening it by pressing the power button briefly. This seems to work ok and doesn't require a power off. I haven't had time to research it further (the reason I found your posting) before this and had presumed it may be a Snow Leopard thing as it didn't so it before upgrading to OSX10.6. Sorry this isn't a fix. I'll reply again if I stumble across a solution!
  • codyk23 Level 1 Level 1 (0 points)
    I stumbled upon another similar thread today:

    So, it's possible that it may have something to do with bluetooth.
    I'm using both a wireless keyboard and mouse, so this may have something to do with it.
    Maybe I'll try plugging in a wired mouse and when it doesn't wake up from my wireless keyboard, I'll try clicking my wired mouse to see if it will respond.

    My only worry is, all the new iMacs basically ship with both wireless mice and keyboards, so why are very few people getting this problem?
    I've also got an external hard drive plugged in all the time, so I'm wondering if that has anything to do with it.
  • scalawag Level 1 Level 1 (95 points)

    I have the exact same thing happening on my 24" 2.8ghz imac as straightshooter. Screen flashes up briefly then black screen that is only remedied by hard restart.

    I have a magic mouse connected via bluetooth, however I have a wired keyboard and this can happen with either mouse or keyboard being used to wake the Mac.

    Again sorry this is not a fix but I hope it adds something.

  • runner2404 Level 1 Level 1 (0 points)
    I have the same Problem. I have also the newest OS update from yesterday but it doesn't help.
    I see in the syslog that there are running some backup jobs but my keykoard and mouse are nor working and the screen is black.
    In this Situation the only way to "wake" the mac is to press the Power button for 5 sec.
    Has anyone a Solution?
    Has anyone asked the Support hotline?
  • un1xfool Level 1 Level 1 (5 points)
    http://support.apple.com/kb/DL1018 attempts to address the wake-up issue (dated Mar 29, 2010):

    "improve sleep and wake reliability when using Bonjour wake on demand"

    Message was edited by: un1xfool
  • runner2404 Level 1 Level 1 (0 points)
    Thanks for this hint.
    But pity!
    I have installed this update before i asked in this Post.
    Any other Ideas?
  • jice0 Level 1 Level 1 (10 points)
    Also see this on a new 21.5" iMac with wireless mouse and keyboard. Have turned off sleeping for now.

    Haven't tested since the update. Will in future.
  • zizz Level 1 Level 1 (0 points)
    My 27" I7 imac has done this off and on since I got it in late December 2009. There were several other threads about this before Apple released a firmware update. That firmware update eliminated the problem for a time, but it returned.

    It worsened - that is, went from intermittent to constant - after I attached a 2T gdrive as my time machine back-up. In addition, I can't wake my machine unless I unplug the power cord and leave it out for a minute or so.

    A couple of weeks ago, I took it to the genius bar, and they found a sleep error code when they ran some diagnostics, but the techs there can't replicate the problem. They reset the SMC and sent it home with me. I set computer sleep to "never" and the display sleep to an hour. This work-around is the only thing I've found that lets me spend more time using the computer to get work done than on getting it to start. I hope it's not bad for the machine to never put it to sleep.

    Apple, if you are listening, you know this has been a problem on these machines since you started shipping them. Please fix it. Thank you.
  • DrGreen Level 1 Level 1 (0 points)
    Have a look at this thread, a lot of people have the same problems... And the very last firmware (April 14th) doesn't seem to change the situation...