I've been having exactly the same problem for many months now, and have highlighted the possible cause to Apple on sending in regular crash reports. But it persists despite despite several Lion updates.
Like CarlaBlue, I eventually tired of asking Apple geniuses about it and took it in for a diagnostic check. Nothing wrong with the machine, the technicians rebuilt the file system and repaired permissions and -- for a brief, shining moment -- all seemed fine.
Then it all started again.
I've done several clean reinstalls (on the technicians' advice), regularly repair permissions and have installed all available combo updates. Nothing, it seems, works.
As a longtime proselytiser for Apple (I've fought hard, though not always successfuly, within companies to maintain use of its products when cheaper alternatives were being pushed for by higher management), I find this annoying. My "stable", Unix-based iMac is now barely more reliable than the OS 9 machines I used to support.
Is Apple now too big to listen?
Read this link (it's massive).
There is a fix from a Polish guy (about page 15!) that has worked for most.
The problem is a faulty driver that Apple refuses to fix on the Radeon ATI gpu.
@dmaude and George, thank you both I am glad there are more people now coming forward with this problem.
George, I believe you are right, I came to that conclusion several months ago, it is a problem with the GPU and my ATI RadeonHD 2400 and something wrong with the driver, maybe a kernel extension.
And I came to that conclusion when I noticed that if I turned off Firefox "hardware accelaration" the browsers prefs would not freeze but it happens with,e.g. Photoshop, when I use tools that pull from the GPU.
I am going to read the link you left here.thanks
dmaude: I installed Techtools and Diskwarrior, and now ran it periodically after my radical clean install where I brought all my files manually without using time machine nor migration assistant and installed all my apps from scratch.
I am a web artist thus I am not even using much of my 250GB, I have 200GB free and 3GB memory.
No bad blocks, no problems with fans nor temperature, I download all updates, absolutely nothing.
It is a virtual freeze and I am almost sure it started with snow leopard 10.6.3 update.
What I did though that seems to alleviate the problem was to install this tiny program/app called "caffeine" that stops my imac from entering sleep and so I still get the freeze but it happens less times. I leave here the link, maybe it helps you because I got so tired of this problem that I did not even want to upgrade to Lion.
I filed many bug reports to Apple, no response. I found a link from 2007 related to something similar and where Apple finally confirmed it was their bug, as stated there:
"Apple technical support has already confirmed the issue with several users, according to the threads, and the problem reportedly has been narrowed to the ATI Radeon HD cards inside the iMac."
I can't say I trust Apple as I used to...
Thanks for the Caffeine tip. I'm sure you're right that this particular set of problems dates back to 10.6.3, and your other link suggests that Apple has learned little about customer relations in the last five years.
This used to be the sort of behaviour one expected from Microsoft or software firms such as Quark. Such operations tend to feel invulnerable at first, but loss of trust -- even amongst relatively small groups of users such as ourselves -- can ultimately prove very damaging to their businesses.
Perhaps we need to shout a bit more, rather than resorting to somewhat desperate measures such as trying to roll back the graphics driver (I think I tried that in the wee small hours one morning, probably fouled up some small step and had to rebuild my whole system... again).
This is just a maintenace recommendation that lots of us neglect:
As old as your iMac is, have you cleaned out the dust? Dust buildup can lead to over heating issues. Remove any and all things plugged into it including the power cord, Remove the RAM access grille. Vacuum all openings starting with the RAM access area (air intake). Vacuum all ports and plugs, DVD slot and the opening across the top of the rear of the body. Blow compressed air through all your openings and vacuum again to remove any dust you loosend. Reinstall the RAM grille. Plug in the keyboard and mouse if not blue tooth. Insert power cord...
You are now in a perfect position to do a
- Shut down the computer.
- Unplug the computer's power cord and ALL peripherals.
- Wait 15 seconds.
- Attach the computers power cable.
- Wait another 5 seconds and press the power button to turn on the computer.
- It is the 5 second timing that initiates the reset.
Here is a Widget to monitor your temps and other operations:
@RRFS Hi,thanks for the tip but in my case that was not a maintenance I neglected as it was exactly the first thing I told repair to do.Absolute cleaning of dust and check my memories as I have an extra one and check for bad blocks, this was done in December 2011.I would not even do it myself and left it to professionals.
Brought computer home opened it and there it was again.
I even installed Tiger again just to check and like that all it was fine.
Only then I posted on this forum.
Issue still happens.
I use iStat Nano to check my fans and temperature. GPU is always around 49ºC, CPU at 39ºC and today ambient temperature is 26ºC. I often check my hardware with TechTools or apple hardware test.
I will check your link.
SMC RESET, no more please, I done that back then also. It did not solve the problem.
dmaude, I don't know if you cleaned your imac like RRFS just suggested to me now, I did all that, but maybe you want to check and also use a widget (I use istat Nano) to check your temperatures.
Also I had to quit using thunderbird and Firefox is no longer my default browser, I use it only to check some things.Thunderbird freezed my mac a lot.
I will keep reporting to Apple, I don't want to mess with kext. files like in that thread for 24" imacs and as the issue is more or less under control I'll wait and see.
( I misplaced this answer)
Hi George, I believe you are right, I came to that conclusion several months ago, it is a problem with the GPU and my ATI RadeonHD 2400 and something wrong with the driver, maybe a kernel extension.
I read the link you sent,thanks— I had seen it previously but I don't want to mess up with kext. files by myself.As it is more or less under control I will keep filing reports to Apple.
Hey George, just came back to say that unfortunately I cannot try the kext. solution, my Snow Leopard DVD is from 10.6.3 because my previous one got a problem and I had to purchase this one. So now I have the bad karma cd.
I'll survive with my caffeine app and prevent my mac from entering sleep until I'll buy a new computer. But thanks for the tip..