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

Same problem here:

iMac 27 inch (2011 - 3.4Ghz, 2Gb Vram) with Lion

Most of the time I start a video (Quicktime, youtube, several websites) the iMac just freezes.

Mousepointer will move, but nothing responds. Not even the Apple-logo in upper left corner.

Need a hard restart (switch on back of iMac).

My fresh-installed Lion iMac 27" 2011, i5 3.1 GHz, 8GB has huge problems playing back videos in Safari. Not only flash related, am using the HTML5 youtube videos. Once it froze, only mouse cursor could be moved, nothing else worked. I am experiencing significant stuttering, not network lag/ buffer related, while playing back videos in Safari. A fix would be most appreciated.

It's been 3 days since I remedied my IMAC and everything is working great. Read back to my other threads to see what I did to fix it.

I have the same problem.

Flash de-installation + PRAM-reset + safe-mode-Reboot did not help.

mattfromnewtown: you might be still in safe-mode (shift-key while rebooting). In this mode you don't have GPU-acceleration. Since it seems to be a GPU bug, it's no wonder you don't have problems. Running in safe-mode is no solution to the problem.

New iMAC 21. My first Mac. Worked great on 10.6 for the first month. Upgraded to 10.7 the day it was released. Video freezing as reported on this thread. Waiting for a fix from Apple since there is no work around beyond turning off video acceleration. I'll just keep hitting the power button until then or use my Ipad for video.

It's not that drastic just turn off sleep in energy saver.

Annoying for sure.

It's not that drastic but when you pay $1200 or more for the best iMac ever, and you can't use normally the best MacOS ever, I think it's really annoying. And when Apple don't give us any information about that, it's really really annoying.

Same problem here. 3 week old iMac 27", all maxed specs.

Freezes (only mouse pointer moves) after playing video content.

Called Support about it.

For now I've turned off sleep in energy saver and will reboot.  Hope that helps until they get a fix out (sounds like a video driver problem).

same here. I have bought iMac 21.5' for $1199 just yesterday, updated to Lion, and already got 2 freezings. They occured at the time when I opened website in Chrome tab (first time it was youtube, second time it was 3 tabs with different sites, and one of them still was youtube). And yeah, I still can move mouse pointer, but when I click it doesn't react. The only way is just to turn it off

Same problem for me with my 27" iMac, Lion and 16GB. It has occured twice when attempting to watch a video via YouTube. Only way to *fix* it is a cold reboot. 

Well, I can report the exact same behaviour (system freezes exept mouse cursor) on my late 2007 20" iMac (iMac 7,1), 2,0GHz Core2Duo, ATI Radeon HD 2400 XT 128 MB, Mac OS X Lion 10.7 (11A511).

This is looking more and more like an ATI driver issue in Lion. 2007-2011 Macs with ATI are the majority of the reports. Spoke with AppleCare today, they are escalating this up to the engineers. Just a simple Software Update patch or something, anything.

After speaking with Apple, it doesn't sound like many of you are reporting this issue. This was the first time they heard of it when I reported it to them. They had a hard time believing it was such a widespread issue, until I pointed them to this forum discussion.

If you want it fixed, REPORT IT!

I filed an bug report at bugreport.apple.com, where I also included links to this forum. Hope that it will be fixed ASAP.

@schihei - You have to call them to get them to move on it. The engineers are busy with other things, and the bug reports get attention eventually. When the AppleCare techs start escalating these up to the engineers they will focus on this immediate fix first, since it is well a very BIG BUG. A system freeze is pretty much a deal breaker in any OS.

@moebis - Ok, will call them tomorrow, too. I agree. A system freeze is really a BIG BUG!