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

same thing here. I have a late 2009 imac and it freezes completely many times during video playback... Dont know what to do... Many programs dont even work anymore.....
This lion failure reminds me the reason i left microsoft ( windows vista....).

Hope we get a service pack or something soon.......

Interesting!!:

Apple replaced my new imac 27 3,4 i7 with this problem:

with a new one!

But the new one has still the same problem!!!! Weird!!!!

What should I do?

Let it be replaced again???

I get that too on iMac 27" 2011. Plus a messed up menu bar and Command-Tab icons after playing a movie in a browser.

10.7.1 may have fixed some problems, but not all of them.

Same problem, except it also freezes when using audiofiles in itunes. Untill Lion not one single freeze, after Lion 10+ freezes a day. Updated to 10.7.1 had no effect at all, like using **** to drive away flies. However my Macbook Pro has exactly the same setup/software as the Imac and has no freezes..(yet)

Reinstalled Lion (after going back to Snow Leopard) and updated to 10.7.1.  It's been a week and no problems.  I'm still holding my breath, but I'm thinking that I might be OK now.

There is an iMac Graphics FW Update available right now that should fix this issue. Give it a try.

iMac Graphic FW Update 3.0

http://support.apple.com/kb/DL1444

About iMac Graphic FW Update 3.0

This firmware update fixes a graphics issue that may cause an iMac to hang under certain conditions.

Do not shut off the power on your iMac during this update. Loss of power could result in your iMac failing to start up.

No it is not for my iMac 2011 3.5GHz  i7 

I have this same issue, only since updating to Lion, I dont think its the machine itself but for whatever reason apple is yet to release a fix for us, since the iMac Graphic FW update 3.0 doesnt apply to us.

sandy-bridge 3.4GHz core i7 here

The firmware update DOES NOT work on the mid-2011 27 inch iMacs. It doesn't detect my hardware.

Yeah the video locking up the machine doesn't happen anymore (mid-2011 iMac 27), since 10.7.1, but there is a BIG overheating issue. The screen now goes screwy and purple background will appear on the toolbar and Apple logo, like a mixed video signal or bad cable, but this is purely a GPU problem. They need to update the SMC fan parameters and give us a good GPU firmware update. I have yet to hear my fans speed up even when rendering for hours, but I can watch the CPU and GPU temps rise up to 180 degrees without the fans kicking in. This is part of the problem.

I don't think anyone has posted this yet?

http://www.tuaw.com/2011/08/24/apple-releases-imac-graphic-firmware-update-3-0-t o-address-hangi/

Firmware update released today.

Yes, read about we briefly talked about it. It seems to be for only 1 model iMac, this fixes like 25% of the problems out there, it won't run on Mid-2011 iMac 27" machines.

Why has this thread become so quiet?  Is it because no one is experiencing freezes since 10.7.1?  I just had my first freeze since updating to 10.7.1.  Same as before:  Display locks up and mouse cursor moves.  Keyboard unresponsive. 

My Mac is 2008, so I am thinking the update only benefits new machines with newer hardware.  I think the time has come to ask for my money back on that Lion download.  How do I make that happen?

It's official:  I hate LION.

I got a 2nd 27" iMac (3.4GHz/4gb/256+1TB/2GB) and first thing I did was update to 10.7.1.  No more freeze problems but I still get artifacting and graphic issues.  Here's a screen cap of my dock:

Same here. No more locking since 10.7.1, but there is still a BIG GPU issue. Like I said I think it's a SMC overheating issue. I've watching the GPU and CPU go up to 180 degrees without hearing the fans speed up. Here is a screenshot of my GPU artifacts: