System Freezes Randomly after 10.6.3 Update

I had this problem once I did the 10.6.3 update. I tried some of the fixes that were suggested but when it hadn't been resolved by 10.6.6 I reinstalled Snow Leopard and did the combo update to 10.6.2 and all was well again. However there were features in later updates that I wanted, such as Apps, so with some trepidation I updated again to 10.6.7 and then bit the bullet and installed Lion. That was about two months ago and I can now say (touch wood) that with only one spontaneous shut-down that I can't explain, everything seems to be running smoothly. I note that a few users have said that they still have the problem after installing Lion, but that is not my experience. The only gripe that I have is the number of older applications that wouldn't run under Lion; Apple could have made this clearer in its release info.

For the record, my Imac is the 20" Alu Core Duo model of late 2007 with a Radeon 6400 graphics adapter and 4GB of RAM.

Team G23 - I'll be interested in hearing where you end up ... I am exactly where you are iMac Mid 2007 (20" 2.0 GHZ Intel Core 2 Duo, 2 GB RAM), upgraded to SL. We've been thinking it was our HD. I've erased and reformatted and reinstalled everything and still no go. It's almost worse than before. I think I restarted 6 times today alone! I did a Verify Disk today and it came up clean. We've been debating on getting a new one or installing new HD and more RAM. But, that doesn't seem to be the issue ..... can't wait to hear the update!

Hey CUinAL. I'm glad I had a Sunday free to work on this... In my second Apple Express Lane tech support call, we:

1) Diagnosed the hardware (in my case, since my iMac originally shipped with Tiger, I needed to boot from the original packaged disk 1 (of 2), holding down "d" during restart to bring up the hardware diagnostic.) I was also worried that the graphics card was maybe having problems after reading another post, but the hardware checked out. I unnecessarily upgraded my RAM from 1gb to 4gb - wasn't related at all, but hopefully it will help keep the 4+ year old computer going a while longer. I also found some

- Good news that it's not the hardware. That seemed obvious due to the fact that I'd never experienced any freezing using Tiger.

2) Clean erase and install of Snow Leopard - A couple of weeks ago, I had erased and uninstalled before, but didn't realize Time Machine backed up the good, the bad, and the ugly, so when I restored, I restored it all and the problem persisted. Today, I erased and installed (still downloading the Snow Leopard updates, 1.09gb). I'm planning on using Time Machine to drag and drop over bits at a time of just what I need: documents, pics, tunes, movies, necessary apps, etc... leaving all the extras, system stuff and old settings alone. Installing and updating alone has taken 6+ hours on my DSL connection, so leave that for overnight if you've got a slow connection.

I'll repost if this doesn't work. The Apple rep said that I have 90 days of support available to me from my Snow Leopard purchase date to receive support via phone or at the stores. I hope I can fix it without going to the store. Good luck!

I have done all that you have Team G23 including multiple reloads, all clean installs with no time machine migrations. Everytime the problem returns after 10.6.3 updates. Patching 10.6.2 ATI kext files allows me to keep updating to 10.6.6 but after this I get Kernal Panics. Lion 10.7.0 - 10.7.2 result in the same random freezes. So I have returned to 10.6.6. I refuse to buy a new Mac as I have now lost all faith in Apple.

My clean-erase and install did not work out as the rep and I had hoped. It froze while importing photos from my iPhoto back up in Time Machine. I didn't use the migration tools, I just dragged and dropped from my external hard drive and after 32,000 of 35,000 photos, it froze, and even messing around afterwards, I could get it to freeze pretty regularly using Safari and Finder. I did the erase and install again last night, but haven't let the software update from 10.6.3 to 10.6.8, and oddly enough, it's working so far, no freezes. I did migrate apps, documents, music, movies, & pictures - no settings or other files. iPhoto won't show the previews of the photos when I click on them, though I can find the photos secondary-clicking "show file". That's a weird side-effect I hope will repair itself after a restart. I'm hesitant to download 10.6.8, but need to if I'm to use the new Trackpad. (We bought a Trackpad from the Apple store to replace our dying mouse, realized (when we got home) that we needed to have Snow Leopard for the Trackpad to work, bought Snow Leopard, and that's when our $1,300 computer became unreliable.) I can't jump straight into Lion from 10.6.3 because there's no App Store on .3. I really don't want to visit the store, since it's not so close and I don't have hours to spend there reexplaining myself and getting nowhere yet again...

If I get anywhere new, I'll repost again. I still think Apple's better than anything else out there, but this has definitely downgraded my confidence in them since they're now just throwing darts at this issue that's killed my iMac.

One more update here... I've erased and installed yet again, without importing ANY data from my backup. I updated to Snow Leopard v10.6.8, and without any of my prior data, and not installing anything other than the OS, I still had a freeze once already, (launching the Applications shortcut tab, oddly enough). I'm going to make an appointment at the Genius bar at the Apple Store to have them take a look. Hardware and disk verifications are clean. Good luck to y'all.

TeamG23, when I updated to 10.6.8 I didn't hang around there, but went straight ahead and upgraded to Tiger. After about six weeks and only one small glitch, everything is running smoothly. I note here again that freezing only occured in my iMac. I did simultaneous updates on a Macbook and Mac Mini without problems so I remain convinced that issue is with the graphics adapter, probably memory management.

Good luck with the Genius Bar. I hope that you let us know of the outcome.

sooo ... Pardalote .... you upgraded to Lion and don't have any problems?

CUinAL, no problems for me so far, but I note there are some posts saying that others have upgraded with mixed results.

So, this has been driving me nuts for a long time. I have an iMac7,1, and after upgrading to 10.6.3, then eventually to Lion, I suffered many sudden freezes of many types. Sometimes I would get wierd lines of different colors, somtimes just black, sometimes a freeze where the mouse would work, and sometimes a complete sudden shutdown. I went down so many roads, thinking it may be diferent apps I was running at the time, the airport, the USB, etc. I even brought it to Apple for help, they could not reproduce the problem! Then I enabled remote access via ssh, and when it froze, I could still enter commands, so it led me to believe it was graphics related. And the errors in the syslog showed GPU faults. Now the question is why? One forum said starting at 10.6.3 the GPU was being overclocked, causing it to overheat. Sounds plausible. The same person added the SMCfan control app and hiked up the fans. I have had some success with this, but also have had several hangs too though (just longer times between hangs). When the GPU heatsink gets around 105+ F, things get dicey.

I'm super frustrated that Apple will not address this. I'm thinking of replacing the graphics processor, but not sure what is involved.

Oh, and I also reinstalled Tiger, and never had one problem. But I got sick of being so outdated, and could not access my iPhoto libraries cuz I updated them in Lion 😟 So, back to Lion, and the fan control... and hoping Apple has a fix soon!

@friedmania

I have had the freezes occur at completely random times which have even included startup. Whilst I agree it is a GPU issue I don't think heat is the cause. It may make it worse but at startup the GPU would hardly have got going.

I also came to the conclusion it was video as I was able to use finder on another machine to access network shares and brwose around the iMac whilst it was frozen. I could also see that download that had been in progress were continuing to download. I've also noticed audio if listening to music or a film continues after the freeze.

I really doubt Apple have an intension of fixing this, and the longer it goes on the less likely that is to change. I've had this issue for over 2 years now and Apple just bury their heads in the sand and ignore it. As far as Apple are concerned its buy a new Mac. 😟

So check out this thread: https://discussions.apple.com/thread/2384136?answerId=16959785022#16959785022

I came across it and follwed their lead and its working great so far. I guess heat was a red herring. But replacing three ATI kernel extensions with the 10.6.2 versions did the trick. It was pretty simple too, you can do it from a command line. Here is what I did.

Make sure your remote login (SSH) is allowed in your firewall settings. Then if your display gets hosed, you can still run commands from another system, in my case, my macbook.

Download this file: http://krzysztof-turek.com/apple/1062atikext.zip (thanks KrzysiuTurek!) and select the files for your mac. Mine ended up being:

ATI2400Controller.kext

ATIFramebuffer.kext

ATISupport.kext

Copy them over to your iMac via scp, or something.

Copy them into /System/Library/Extensions/

Change own/perms: chown -R root /System/Library/Extensions/ATI*

Change extended attrtibues: xattr -src /System/Library/Extensions//ATI*

Clear cache:

kextcache -system-prelinked-kernel

kextcache -system-caches

Reboot.

You can reference the thread I mentioned for more detaols and such. You can use a graphical kext helper tool, but since this problem was so bad, I could not seem to get enough time before it would freeze!

I kept a copy of these kexts in /var/tmp, so in case an Apple update clobbers them, I can just move them back. Hopefully Apple/ATI will get with it and fix this PITA!

Good luck!

Phil_O, I share your experiences and sentiments completely. At present my Imac is running smoothly under Lion, but if it starts freezing again I will be going straight back to 10.6.2.

There is one thing that I haven't mentioned previously, and that is that I frequently use the iMac running Windows XP from Boot Camp. I do this because there are CAD and a few other programs that I need for which there is no Mac alternative. As a Windows machine I have never encountered a freeze or any other glitches. This to me says that the hardware is not at fault, that the machine management is OK, that the Windows drivers are OK, and that the problems we have experienced under OS X are of Apple's making. They should stop treating us like mushrooms.

If all else fails I will never ditch my Imac because it makes a **** fine Windows computer!

Stubborn me... I did yet another erase & install, and restored absolutely nothing - froze. Updated as far as possible - froze again. Upgraded to Lion, and it seemed like everything was going well, then it froze with vertical green lines (?). Restored data (music, photos, movies, docs ONLY), worked well for hours, but then randomly froze while navigating in Finder, doing nothing too resource-consuming. With each of these, I had to manually power down. I made an appointment at the Genius Bar for Monday. (Fingers crossed).

(Story of how it all went wrong: Our USB mouse is slightly damaged, so we bought a Trackpad $50, realized we needed Snow Leopard $30, bought it, installed it, freezing began; upgraded from 1gb RAM to 4gb RAM $40, spent 10 days trying to fix the problem with this post and with Express Lane, got nowhere; downloaded Lion OS X $30, freezing still. $150 later, I've killed my iMac basically. (Should'a stuck with Tiger and bought a replacement USB mouse on eBay! Priceless! Would have 10 days of my life back and $150...) )

You have my sympathies TeamG23; it is my fortune that I am still having success with Lion.

Is the iMac/OS X 10.6.2+ fit for purpose? Maybe it is time to rattle Apple's collective cage and start discussing a class action. I would be happier if they just owned up to there being a problem.