Q: OSX Lion + 2011 iMac 27'' + Video = Freeze

@J Motts: I had it set to 'based on input device' but have changed it to 'when scrolling' as yyou have described. Hopefully it changes something as I have had two crashes today in the last three hours alone.

My less-than-a-week-old 27" iMac has also been having the exact same problems.

I had my scroll bars set to "Automatically based on input device" and just changed to "When scrolling" as per @JMotts' advice.

Will check back in soon to confirm that it works.

Fingers crossed! (And thanks for the help!)

I followed your instructions.  My applications still hang, but not as often.  Didn't completely solve the problem.

Looking forward to trying that. I'm waiting for my Crucial RAM to come back from RMA. Fingers crossed, but not really holding my breath.

Here's a question for everyone. How many of you with the problem have been in touch with AppleCare or Geniuses? If you have been, what are they telling you?

Changing the scrollbars apparently did not help as I had two crashes this morning. Was worth a try, though! :-)

I have called AppleCare twice and had my iMac been 'repaired' by the Geniuses once, neither had any solution to the problem or had even heard about it.

Disappointing so far - I thought it was too good to be true!

The reason I posted this was that my iMac froze in exactly the same way as others report every single time when trying to load any kind of movie (when it had been to sleep since start up), after I had made that change to the scroll bar setting.

Changing the setting back completely cured it. Clearly there's something relevant in there and maybe there are other, apparently irrelevant, preference settings causing users problems.

I think you are correct that there are multiple issues here.  I have found one thing that appears to be consistent on my 2010 27" i3 iMac, though: once the machine has frozen, the Power Management Controller and PRAM will be messed up.  I will continue to experience freezes consistently until I reset both, and then the machine will be stable for a while again.

I've turned off all sleep modes my iMac for the time being, and have turned off Wi-Fi.  These changes, in conjunction with a PRAM reset seem to allow me to work for an extended time without any freezes.  Once it starts freezing (usually after I log out, and my daughter logs in to her account - she likes to view YouTube videos a lot, so there may still be something related to that), it will NOT be stable, regardless of the account used (I also have a "for repair" Admin account on my Mac, that runs no extensions), until after the PRAM is reset.

Oh, one other thing...in checking my system logs, many of my crashes are related to the PMC.

Geez, I too have a 27" iMac with Lion and it's freezing constantly in all applications. Apple Store even swapped out my hard drive but that didn't fix it.

Does ANYONE know of any kind of a fix?

i Have mac mini old version intel cpu, work well with lion but new imac 21.5 or 27 have problems with lion and is not one person is all imac model new version i change in 3 month two times the imac in apple store and the same issues the first in sept come with snowleopard issues freeze, the second one 5 days ago with lion freeze. is the hardware do problems with lion and snow leopard on imac

I have not waded through 86 pages of this thread, but suggest a good starting off point is to make sure your system is up-to-date, with downloads from the Apple Support website.

http://support.apple.com/downloads/#imac

> I have not waded through 86 pages of this thread [...]

You should have... :-)

You should read is not one person problem, 8 hours ago i call apple care support really garbage that people dont understand what is the problem with imac and lion, i follow the instruction but now my imac dont do nothing now have boot problems when apple care toll me to check the hard disk with  disk utility hacpve error impossible to fix that happend after computer freeze and try to do hardware test now is for garbage i lost 3 days of hard work with my web page the stupid senior advisor toll me you need to pay for recover your web i toll him not problem i do fresh installation for lion i know i lost my work but today you lost a client and come back with the imac to the store for refund my money and buil one nice windows computer.

Yes come back to the store for refund your money or install snow leopard until the apple fix the issues on lion, if you have wifi problem only in lion downgrade the driver for wifi to 3.2 version

Cantellolo wrote:

 

> I have not waded through 86 pages of this thread [...]

 

You should have... :-)

This thread started July 20th, the day Lion was launched, Apple have issued two operating system updates and several graphics and firmware ones since then.