24" iMac Screen Freezes since 10.6.3 update - pls help!

Update on my USB External Drive. Not the problem. System was behaving very well until this morning when I was using the computer. POS 10.6.3. Mind you, this is a system with no software installed, other than 10.6.0 leopard clean install, 10.6.3 combo update.
Attached hardware: Stock apple keyboard and mighty mouse on USB.
iMac 8,1.
My father, my mother and my cousin have the same computer, 24" imac 8,1, same problem, only since updating to 10.6.3
What can I do?
Oh and my PRAM has been zapped so many times it's probably gone 😉
SMC reset done many times.
The problem is not there when I use up to software 10.6.2, so there!
It cannot be external hardware, nor can it be exotic software as there is nothing installed but apple stock 10.6.0 with update 10.6.3 combo.
Hardware test run without error.
Anyone still doubting it's a problem concerning 10.6.3 and imac8,1?
It may affect more systems, but I only have access to the 3x imac8,1 and a macbookalu which does not have the problem at all in 10.6.3

I have had the same problem for some time now. My computer has been sent to Apple for repair two, times. They changed the graphics card and the hard drive.

They are still not able to fix it, and have agreed to replace my iMac 24" with a new one. Im currently awaiting my new computer.

I am sorry that this doesnt help any of you.

Gone back to 10.6.2. So far . . .no problems at all. NO FREEZES!

How can I tell if my iMac is an 8,1 model?

Mine seems a little more stable since I did the 3 x PRAM thing, but then it always seems totally stable up to the point where it freezes.. 😟

(Just discovered this topic.) I just got back from the Apple store Genius bar. I had the same problem. They told me to install 10.6.2 and not go to 10.6.3. I had to reinstall from the Snow Leopard disk, then upgrade. They said Apple knows about the problem and is working on it. (I hope this works!)

Just an FYI - I tried leaving my Time Machine backup drive unplugged (a WD 1TB My Passport, USB) when using the machine and have not gotten any freezes AT ALL in the last 10 days!

I had noticed a trend for the graphics glitch to happen shortly after waking the machine - this also corresponded with Time Machine spinning up my external drive. I could hear my external and internal drives spinning and writing when the freezes occurred.

There might be some sort of software glitch between the "improved" 10.6.3 Time Machine backup process and either RAM or the graphics card... how these tie in to each other is really a mystery at this point. It makes sense that this glitch starts happening when we either use our machines for a while or boot them - triggering a Time Machine backup event.

I do not think it's a coincidence that the top "priority" issues that the first 10.6.4 build reportedly is addressing are (you guessed it): "*Graphics Drivers*, SMB, *Time Machine backups*, USB, and VoiceOver." Three of those issues more than likely tie directly into the problems we are seeing here.

Just as a side note - this drive is only about two months old. It works perfectly, passes all WD hardware tests and I use it regularly on three other machines in my house, none of which have this issue. Only when I plug it into the iMac with this issue.

Here's to hoping that at least we have found out what the culprit was here. I urge everyone here to at least give it a try - unplug your Time Machine backup disk and only use it sparingly. Hopefully I don't have to amend this post with "well, that didn't work."

Have *iMac 8,1*. 24 inch. Was running fine until three days ago. Started to freeze randomly watching movies and playing games at the times, couldn't force quit.
Either had to wait a couple minutes for it to recover or hold the power button if it didn't.

A day after the freezes started, the graphs got messed up. On the right side of the screen rectangle lines started to appear and everywhere yellow waves appeared on the screen. The same day, when rebooted the computer fail to get the the login screen, it freezes right before.

Safe boot works but graphs errors are still there. Checked the hard drive, reset the PRAM and SMC, still nothing. I had a feeling the graphics card got fried, so I took it to the apple store and they agreed it was the graphics card.

Now awaiting repairs. Btw it cost $400 for a new card (*nvidia geforce 8800 gs*) and $85 for repairs, tax not include. My question is why did the graphics card die, was it from the SL 10.6.3 updates because $400 for an older graphics card is ridiculous.

Message was edited by: Gruenhagen V

Message was edited by: Gruenhagen V

I got a hold of 10.6.4 through a friend who's developing for apple.
Until now no problems.. Hope this beta will prove to be reliable.

I feel your pain. I started having this issues shortly after upgrading to 10.6.3. I am not sure that is the reason why the computer crashes, but it seems to be since so many users are having the problem.

I tried everything on this post and then some, I called Apple Care, they were really nice and walked me through some possible solutions, unfortunately nothing worked, I even formatted the computer back to 10.6, the ran system update and the pain was still there. Apple Care recommended having the HD checked at the Apple Store where they ran deeper HD check, the test proved a failure in the drive so I got it replaced, they said it was ok to update the system and even restoring it from a Time Machine back up.

After the update, I let the computer fall asleep and once I woke it up, it froze again, full screen on gray this time.

I will be calling Apple Care, I believe is not a hardware issue, hopefully version 10.6.4 will fix the bug, but in the mean time, I am dodging the freezes by keeping the computer awake (using Caffeine app), and turning it off overnight.

*I have been able to work through several hours with no freezes, just keeping it awake.*

Good luck, and patience.

Ref. Link: http://lightheadsw.com/caffeine/

cvdgenugten wrote:
I got a hold of 10.6.4 through a friend who's developing for apple.
Until now no problems.. Hope this beta will prove to be reliable.

So it did work for a while, but the update to 10.6.4 didn't work.
This does not automatically mean it's not going to work for the 'real' update off course.
Also take into account this was a delta update, so really, it's supposed to fail isn't it?
It built 10.6.4 on top of the 'faulty' 10.6.3.
2 freezes today with it.

I reinstalled 10.6.2 just now and whooot, that's the way my imac will stay until someone posts that 10.6.4 has been released and fixes all our issues concerning the freezing.

Gruenhagen V wrote:
My question is why did the graphics card die, was it from the SL 10.6.3 updates because $400 for an older graphics card is ridiculous.

FWIW, I have an 8,1 iMac with the 8800 GS graphics system & have had no problems with 10.6.3, which I installed on the day of its release.

Hmmm.. I thought I remembered you having a xt2600 card in your imac 8,1.
I wonder if it has something to do with the fact I have that card.
It's been updated several times (firmware) by software updates. I seem to be running the latest firmware on it. Seeing the issues seem to involve graphic artifacts on the screen for some, it could be related. I have however given up on it. I will wait for 10.6.4 and try it when it releases.
My iMac 8,1 24" xt2600 is running smoothly at 10.6.2 for the moment and will read messages on this board before updating to 10.6.4 as well.
Too much time has gone into trying to find a solution for what has been acknowledged by apple to be a known problem for some computers. I will be patient, apple has not let us down when it comes to support, at least that's my experience..
Just wish I had one of the models that doesn't freeze on 10.6.3..

cvdgenugten wrote:
Hmmm.. I thought I remembered you having a xt2600 card in your imac 8,1.

Your memory is fine. I have two 8,1 iMacs, as listed in my profile below each of my posts. The 24" has the 8800 GS, the 20" has the XT2600. They are "his & hers" computers, one for me & one for my wife, but I administer both of them. Both run 10.6.3 without problems.

My iMac 20" keeps doing the same thing - freeze and then screen with either multiple colored stripes or just black. I thought it was a Flash issue since it always seemed to happen when browsing career builder, with ads on the site. Re-installed Snow Leopard, everything was fine until I did the 10.6.3 Combo update. That's when it started freezing again.

I thought maybe Time Machine was the culprit, so I unplugged the external. A few days later it did it again.

I will try disabling sleep on the machine and see if that helps... but it seems to happen even if the computer hasn't gone into sleep mode yet...

I have the same problem on my 20" iMac from 2007 (ATI Radeon 2400 XT).

I am pretty sure the problem is caused by an updated gpu driver in 10.6.3.
The problem first appeared on april 2nd on my system, after I updated to 10.6.3 on april 1st.
The screen freezes, there is no reaction on any keyboard inputs or mouse clicks, but I still can move the cursor and login via ssh is still possible.

The WindowServer is in the state "stuck" when I look at the process list with top.
The kernel.log shows a GPU debug dump each time the freeze occurs:

kernel[0]: ** Device in slot: SLOT--1 **
kernel[0]: ** GPU Debug Info Start **
kernel[0]: 0x000094c8
kernel[0]: 0x000000d6
kernel[0]: 0x00000001
kernel[0]: 0x00000018
kernel[0]: 0x0000d062
.....
kernel[0]: ** GPU Debug Info End **

I hope we get a fix soon. I think I will switch back to 10.6.2 this weekend.

Sebastian