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

Try  this

Go to Finder "Go" menu hold the option key and choose Library. Then go to Preferences folder and trash these files:

com.apple.finder.plist

com.apple.sidebarlists.plist

then restart  with  hold  shift.  ( Safe mode)

Then restart  again.

This solved my problem

Have a iMac 7,1 and thought it was falling apart until I found this thread a couple years ago. KEXT solution cleared all problems until I recently, accidentally, upgraded to 10.6.8 (which if I remember, was the "unfixable" version) and the iMac starting acting up fiercely again.

Upgraded directly to Mountain Lion 10.8.3 via online purchase a few days ago and haven't had problems since.

Scratch that -- the machine froze (mouse pointer still active) after I posted that.

Installed the kext files and it happened once more while watching a video. Otherwise stable.

I hope 10.8.3 isn't another "unfixable" version.

@Iftokyo

I have my iMac 8.1, ATI Radeon HD2600 pro 256mb, now running 8 days on 10.8.3 combo no freezes

(In previous version had to apply Kext fix!)

Did you use Combo update or the delta (store)update?

Please try the combo update.

Thanks for the reply. I just downloaded ML directly from the App store, upgrading from 10.6.8. Exact version is: OS X 10.8.3 (12D78)

If I wanted to try the combo update would I have to use Time Machine to go back to the previous OS?

@iftokyo

iMac 8.1, HD2600

I first downloaded from the App store, had no problems for a couple days, then based on people's experience, downloaded the combo update and installed it right over the App store version and have had no problems since then (a week or two). Previously, I was running with the kext fix.

That's just my experience.

Thanks for the tip. I installed the combo update on top of the App store version. Will see how it goes.

On a tangent, I'm quite impressed with how Mountain Lion and Adobe CS is running on an old iMac 7,1 (4Gb of RAM probably helps).

Nope, still needed the KEXT fix even on 10.8.3. It froze a couple of times (only mouse pointer active). The anomalies certainly weren't to the degree they were under 10.6.8 but ultimately an Imac 7,1 running 10.8.3 (combo update) still required the 10.6.2 extensions, at least in my case. Fine now!

Just a quick update:

Yesterday I had to install kext fix over the 10.8.3 - because the GPU had crashed.

So the the problem is definitely not resolved. Shame.

Same thing here. Two freezes in an hour yesterday, mouse pointer moving but no action. Hard reboots. Installed kext fix over 10.8.3.

My Problem returnedIn 04/04  i formated my HD   And i instaled full mac os  10.8.3   and i dont have more freeze 

I'm thinking of buying a used 24" 2009 Imac. Are these susceptible and is it best to avoid in favour of a later model?

Looks like the 2009 models have NVIDIA GeForce GPUs while, if I'm correct, the problems and fixes referenced on this thread are with ATI Radeon GPUs for the most part. That would give me more confidence in the 2009. However, my 2008 model works fine with the kext fix (I even took it apart and put a Samsung SSD in it) but I'd be hesitant to sell it to anyone who wasn't an expert able to keep up with this stuff.

I would caution against this since there have been other issues with the 2009 model. See this thread: https://discussions.apple.com/thread/3938355.

Last sunday (after 2 weeks of 10.8.3) my iMac locked with a black screen. A big disappointment!

Have applied the Holy Kext. Used the 10.8.3 combo update.

My iMac:

Model 8.1, 24", ATI Radeon HD2600 pro 256 MB