iMac won't wake up from sleep using keyboard or mouse

i got the same problem but thats not the only problem i had. my imacs hard drive fan is speeding up to 5000 rpm even more than that. The temp was only 37c. Now its on apple shop more wait, and apple would not replace it to another one so im stuck with a 3,000 computer. Oh i got i7 with 8gb ram and 2tb hitachi HD. This computer is a problem its not helping on my work im stuck with my old mini laptop from sony. P.S. Those people online support didnt help a bit. They want me to use my apple care on this computer that has a 1yr warranty on it. Again the computer has a one yr warranty its not even a yr yet why would i want to use my apple care if i got 1yr warranty. So now Im stuck waiting again.

I have exactly same problem, Mac goes to sleep and dont wake up. I have tried wireless mouse and keyboard. Only solution is turn computer off and start it again. But doing this I have to face my second problem. My computer freezes on blue screen for 5 minutes before it starts. Should I reinstall OS to fix starting problem?

Jani

Reinstalling the operating system likely will not help this problem. After running this iMac without incident (except for unreliable CAPS-LOCK key light on wireless keyboard) for a month, I experienced the problem of needing to force POWER OFF to get it to start normally. A couple of days later, same problem, but then I noticed a fan was running slowly, i.e. the system was not really sleeping. So this may be a problem where it doesn't fully sleep, not that it doesn't wake from sleep. Or maybe that's an additional problem. Anyway, I reset the SMC the second time it happened and the problem has not occurred again.

After you power off, pull the plug, press the power button for at least five seconds, plug power cord in, press the power button to restart.

It's possible your system took so long to reboot because it had to rediscover your start disk. Go to System Preferences -> Start Disk to set your restart disk if needed.

Well, I guess I will pile on. I have a 1 week old 27" iMac i7 and it was working fine yesterday morning and I put it in sleep mode to leave for the day. Came home, tried to wake it up, went through all the various secret saucy restarts and it won't start up AT ALL.....NOTHING! Taking to Apple store today. But seriously, it cost me a fortune, it is my first mac and it fails me in the first week? Gah!

have you connected a(ny) firewire hdd(s) while putting the imac sleep ?

since i disconnected the fw device i have no sleep/wakup problems ..

I brought my mac to apple and they fixed the problem. They didnt tell me what they did but its running fine now. The main problem was the hard drive fan speeding up. But they fixed that too.

Sory No change my mac still have sleep problems. Got to bring back again to be fixed.

Update... My imac still have sleep problems. Called technical support talk for 1hr no luck. Now I discovered that the fron bottom alumimun part of my Imac has a deep scratches after apple fixed it. Called that apple store and explained to them, they just told me to bring it wright away. Anyways, this computer is brand new when I got it now it looks like a refurbish computer. Another thing this computer stayed for 1 week on apple shop and still have problems. Hope apple is reading this coz this has been a terrible experience for me having my first apple computer.

Update: Apple replaced my imac to another new imac i7 8GBram 2TBhd. Hope there is no more problem with this one. Now I am waiting for it to arrived. Thank you apple.

I have a similar problem. We have a lab of 16 20" iMac Intel (Mid 2007) running 10.5.8. All the Macs in the building are clones of the same OS and app image and I am only having trouble in this lab so I am pretty sure it is model specific. The problem appears to be not awaking from sleep. You walk up to a machine it appears to be shut down, if you put your ear to the machine you can hear it is on. The only way I have found to deal with the problem is to hold the start button down until you hear it shut off then restart.

Wow! I actually fixed my problem completely! I was having exactly the same problem as all of you and thought for sure the reason was the MagicPrefs program I was using . . . but I got rid of it and still had the problem. It went to sleep but would not wake unless I unplugged and plugged back in. Then I remembered that around the time the problem strarted I switched from a 4 port powered USB hub to a 7 port powered hub. I switched back and the problem disappeared. If I plug the 7 port hub back in . . . the problem is back, so that's the problem for sure. Check to see if you have anything funky going on with a USB hub. It might be that it's just a cheap off brand hub, or it might be the number of ports gives the OS a problem . . . so check your hub if you have one!

No, again I have a whole room full of them doing the same thing only keyboards and mice on USB

Sorry it was not a solution for you . . . it is reproducible for me so it definitely triggered my problem. Good luck though! For me I was just glad I didn't have to drag it over to the Apple store etc.

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

My 27"I7, 2T HDD imac has narcolepsy too. Mine goes to sleep and won't wake up unless I unplug it, etc. Took it to the genius bar and they reset the SMC and sent it home. They can't reproduce the problem. I've had the problem off and on sinc eI bought it in Dec 2009. It got better after the firmware update, then became constant, slipping into a coma several times a day after I attached a firewire 2T gdrive to use as my time machine backup drive. What's very odd is that I have to press the on button twice to get my machine to turn on. The first time just the fan goes. I press and hold the on button to turn it off, then press it briefly to start it. It starts right up. While poking around the apple support site, I came across this:

"Only a Mac running Mac OS X v10.6 can Wake on Demand. New Macs ship with Wake on Demand enabled by default, but for some earlier Macs this option must be enabled using the steps below. Macs that have Wake on Demand enabled will occasionally wake for a brief time, without lighting the screen, in order to maintain registrations with the Bonjour Sleep Proxy. On some Macs, sounds from the optical drive, hard drive, or fans may be heard during these brief maintenance wakes."

I'm not on a network and I don't have a time capsule, nor do I have any idea what a bonjour sleep proxy is. But it does seem that my computer is stuck in a "maintenance wake" when I first try to restart it and sometimes when I think its asleep, the fan is on, so could this be a part of the puzzle?

For now, I just set the computer sleep time to "never" and it is working for now. I've also set my personal sleep time to "never another apple product."