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

Great news Vurey, can you tell me just some last things?

When you did it with snow leopard you changed from running 32-bit to 64-bit? And I should do that before or after apllying the fix?

And are you running 10.7 now? It is just because I want to be practical and upgrade already so as I don't have to do the fix twice, first for 10.6.8 and then for 10.7.thanks

@CarlaBlue, -- Regarding 10.6.8 and 64-bit mode: TK111 is right, we're talking about booting the OS to run in 64-bit mode. You don't have to change any apps. 32-bit apps will still run fine. I first changed to boot into 64 bit mode, and ran that way for a few days to see if any problems occurred (there were none), then applied the "kext fix".

To make my machine boot into 64-bit mode every time, I used a "defaults write" Terminal command. I think you can easily find it with google...

I believe 10.7 (alll versions) run in 64-bit mode by default, so that's why you don't have to do anything special before applying the kext fix in 10.7.

Thanks Brian, I was kind of confused about that.

So I am going to save myself some time because I get the freeze only every 3 weeks now, I'll upgrade to Lion 10.7.4 with a clean install from a bootable install disc, bring my stuff back with migration assistant test it for some days to see how it works and if it crashes I will aplly the kext. fix. Either way I'll report back here in some weeks.

Thanks everyone for the help, I really appreciate it.

20-inch iMac mid-2007

ATI Radeon HD 2400 XT 128MB

OS Lion 10.7.4

@CarlaBlue, I have the same iMac as you. The kext fix doesn't work with 10.6.8 since the 7,1 iMac cannot boot into 64bit mode. If you do this, your iMac won't start...at least mine didn't.

However, it works with all other 10.6.x versions and so far works with all 10.7.x versions. So, if you don't have 10.7, then upgrade to it, since it is cheap.

I also have the 20" iMac 7,1, mid-2007, ATI 2400XT. After upgrading from Leopard to Snow Leopard 10.6.5, I started having the freezing problem every couple of days. I installed the kext fix, and then stopped at 10.6.7 for over a year when I read that the kext fix didn't work with 10.6.8 on thge iMac 7,1 (and even if it had, I didn't want to go to 64-bit at the time, since that breaks Rosetta). The need to upgrade to iCloud finally pushed me to Lion, and I have been running 10.7.4 now for a month with no freezing issues; my current uptime is almost 22 days.

% kextstat | grep ATI

97 2 0xffffff7f8142f000 0x18a000 0x18a000 com.apple.kext.ATISupport (7.1.8) <72 9 8 7 5 4 3 1>

98 0 0xffffff7f818be000 0x40000 0x40000 com.apple.kext.ATI2400Controller (7.1.8) <97 72 9 8 5 4 3 1>

99 0 0xffffff7f815b9000 0x261000 0x261000 com.apple.ATIRadeonX2000 (7.1.8) <73 72 9 7 6 5 4 3 1>

100 0 0xffffff7f818a7000 0x12000 0x12000 com.apple.kext.ATIFramebuffer (7.1.8) <97 72 9 8 7 5 4 3 1>

@richard and geychaner

Thanks a lot for that info, I did not know that about 10.6.8, the reason why I did not upgrade to Lion is just because I always wait 1 year before upgrading OS to give app developers time to correct bugs on their updates, but it is a relief to know this fix will work for our models when upgrading.

I am in the middle of a project and I don't want to risk any troubleshooting, so I'll upgrade next week and see how it goes because so far I've been mostly using my computer to code, really lightweight file handling, and maybe that is why I've been managing to make it stable, but now I need to install cinema 4D and I don't want to handle the same problems on my mac like I had last year. Then I'll report back here and if it fixes I'll report to Apple as well for silently sabotaging my computer for 2 years.

Wow am I glad to find this thread! Add me to list with 20" iMac 7,1 late 2007, ATI 2400HD, 10.6.8 with all exact freezing issues noted.

I have taken mine into the local Apple Store 4 times looking for answers, meeting with the genius and after running diagnostics it says everything is fine. I replicated the problem and then they say to replace the video card it is failing. I have not replaced it as I am stubborn because the iMac works perfect at times, but then freezes past 10 times a day repeatedly. I also have not upgraded to Lion yet because I assumed my iMac was dying and would be replaced soon. I really want return to the genius with this thread information and see what they have to say after 2 years of driving me crazy!

I am NOW very thankful to see the kext fix working for so many people and know that the issue can be fixed. Also happy to see Lion 10.7.4 is stable for others as well. I plan to wait to upgrade to Mountain Lion in July and see if the freezing is fixed or controlled. If not it is comforting knowing I can get to 10.7.4 and apply the kext fix!

Any new info or feedback from others running Lion 10.7.4? Thank you all so much.

Yep, I have the exact same 2007 iMac as you with 2400HD graphics. All the usual flickering, glitches and freezes since 10.6.3.

As soon as the kext fix was discovered some time around 10.6.4 (I think) I installed those three files using kext helper and its run perfectly since. I've had to reapply the update with every 10.6.x and 10.7.x Software Update, but it only takes a minute and a reboot to do so (I just keep the files in a handy folder on my desktop so they're quick to find, as sometimes my machine locks up within a minute of booting if I haven't applied the kext fix).

I'm now running 10.7.4 perfectly. I can't remember the last time the machine locked up. To be honest, it's only lightly used now as I've recently purchased a MacBook Air. I'm thinking about selling the iMac, but will probably struggle to explain to someone on eBay what the problem is and how they can fix it. I'll have to point them to this forum, I suppose!

I guess I'll wait and see whether 10.8 fixes the problem once and for all, but judging by the track record over the last couple of years, I'm not hopeful.

Has anyone here tried using Mountain Lion? I'm crossing my fingers that it's finally fixed. The issue started with Snow Leopard, and Lion never fixed it 😐

It wont ever get fixed. Apple's official line on things is that lockups on ATI 2400/2600 hardware is caused by a faulty GPU - even when it can be demonstrated that the hardware is fine and the problem is solely software.

My personal reasoning on this is that on older ATI 2400/2600, there is a firmware or hardware errata that is worked around by the drivers. For some reason, the fix for this errata has been removed from the newer drivers. Newer hardware revisions are fine - hence why replacing GPU fixes the problem.

I'll note that under Windows I had bluescreens and "display driver resets" for a while using ATI's official Catalyst drivers. At some point, they resolved the problem. This tells me that ATI may have made a mistake and later corrected it, the mistake was passed onto Apple who have not corrected it.

<Edited By Host>

Mountain Lion is released today.

If someone has time and nothing to lose 🙂, please try the kext files on Mountain Lion and let us know in here if the files work on Mountain Lion.

Thanks!

Mountain Lion didn't fix the problem but the kext fix is still working.

Right now I made clean install of Mountain Lion with no Kext replacing. I will let you know when first freeze will appear.

System runs faster than Lion on my machine.

Any word on the kext fix working with Mountain Lion?