iMac screen goes blank, iMac still running

(Reposting, black screen problem just happened as I was typing this)
So, I am not the only one with this problem.
My screen usually shuts down when I am on the internet. The screen goes black and the fans continue to work normally. I will try resetting the RAM and post again if it works...or if it does not.
Ridiculous.
Sad customer. 😟

Another thread with more information more (much more) troubled users can be found here:

http://discussions.apple.com/thread.jspa?threadID=2384136

I will add myself to the list of people having this problem, and perhaps include some more clues. My 24" Intel iMac (with OSX 10.5.8) starting doing this over the past few days. It appears as if the computer suddenly just goes into "sleep" mode. The HD stops spinning, the screen goes completely off, and absolutely nothing will wake it up short of unplugging it and rebooting. HOWEVER, it actually wakes ITSELF up after a couple of minutes.

I called Apple and he had me reset the PRAM. That didn't help.

Here are some other factoids about my setup:

24" 2.4 GHz Intel Core 2 Duo
iMac is connected via Ethernet to a Time Capsule that is used for HD backup and for the wireless/wired network
Also connected are two La Cie hard drives via Firewire, as well as an iphone, Apple keyboard, and MS wireless mouse.

I have just collected a new imac after the last one gave me a hard drive failure sign after twenty days of use. Today my screen just went black and I could hear the machine was still on so I had to reboot to get it back from 'sleep mode'. I am feeling very nervous about this imac now and I don't think I can face the guy in the shop again!

This same thing happened to me recently and the other day the computer shut itself off completely and would not turn on at all. I took it to the Apple store and long story short: the logic board had failed.
It was a 2007 Intel iMac.

I have had this happen to my office machine 3 times now. Since I had a laptop with me this time I sshed into my office machine and ran a VNC server. From my laptop I was able to use the office machine fine but my screen remained black. Using my laptop I opened the Display preference pane and changed the resolution. Bingo my screen was back. Changed the resolution back to normal and am currently going strong.

I still don't know whether it is hardware or software but I thought this might be useful to someone.

Alistair

Just bought my brand new 27" to replace my 7 year old imac and screen blanked before I put in registration details. It then went several tens of times in one evening before I thought I'd cured it by turning down the brightness on the screen. Since then no probs, but I'm only 1 day into my new machine! Having major problems in migrating everything too - another story.

Same issue on my 2 week old 27". Reset smc and zapped pram. i am hoping this will help.It seems there are other users experiencing this issue in various forms. I will monitor this forum for any updates on this issue.

This just happened to me for the first time on my six week old iMac (i7).

I double checked that the machine froze, not just the display, by attempting to connect to the iMac via Screen Sharing (I used VNC from a Windows laptop AND from my iPhone -- neither would connect).

What I am wondering is if anyone else who is experiencing this issue frequently has tried connecting to the iMac from another computer to see if this is uniformly freezing Macs, or if some of them are just getting some display-related issues.

Same deal, only I get the freeze in a few varieties. Sometimes the screen turns blue, sometimes black, sometimes grey. In every instance I can here audio going (from iTunes or Hulu or wherever) and then that quits as well. I've also noticed that when this occurs, the keyboard is no longer getting power (caps light doesn't turn on).

Like the rest of you, I cannot reproduce this problem at will, and the hardware test comes back fine. It was in the Apple store for twice an unrelated problem (persistent screen burn in, it's on its third) so I am beginning to think this machine is cursed. Fortunately I still have Apple Care, but I don't know what to tell them. Very frustrating.

24" iMac C2D 2.8 / 2008

I've been having this problem for about two months now, and that's about how long I've been following this thread. My experience has been about the same as everyone else, although it usually happens when I'm out of the room and I come back into my office to find my Mac dead -- black screen, fan running, keyboard unresponsive, etc. This happens to me at least once five days out of seven, sometimes multiple occurrences in a single day. (Although it hasn't happened today... yet.) I've tried most of the things that have been suggested here, but nothing changes. Fortunately, once restarted the computer behaves normally and nothing seems to have been adversely affected.

Has Apple not addressed this at all? I'm new here and as such don't know my way around very well, but if Apple has addressed this issue, could someone point me in the right direction?

I am having this trouble on my Intel iMac as well. The strange thing is if I boot up in Windows (via Boot Camp), I don't have this problem.

I thought it was a hardware problem, until I ran the machine for two days in Windows without the blank screen/power off problem.

I bought a new iMac 27" i7 3 days ago. On the first day, the screen went blank 3 times, but the computer remained on, playing music. Pressing keys I could hear feedback that the computer was receiving keyboard input, although I couldn't obviously see what I was doing. Each time I left the computer for 5 to 10 minutes and then it would come on as if waking from sleep.

I thought I had tracked the source of the problem to the wired extended keyboard I was using, as when I swapped this for the wireless keyboard that came with the iMac everything went fine, until now.

Three days on I just had another blank screen incident. Symptoms are as before. I was not doing anything unusual or processor intensive at the time. It's been 15 minutes and I am still unable to wake up the screen. I'd rather not do a hard reset, but if it's not back up in the next 10 mins I see no alternative.

This is shocking for a top of the range, brand new computer.

Do Apple monitor these forums?

I just did a hard reset, including unplugging the power from the computer and waiting for a minute and then started the computer up again, but although I can hear the computer starting up the screen is still blank. The brightness keys on the keyboard have no effect. I have shut down and unplugged the computer again and am leaving it for 20 mins before trying again.

I left the iMac unplugged for 30 mins and then started again, but I still get a blank screen as the computer starts up. I can hear that the keyboard is recognised as I get audible feedback using the volume buttons on the keyboard.

This is crazy. The computer's only a few days old. I wonder if I just turn up at the Glasgow Apple store where I bought it with it all boxed up if they will replace it or refund my money?