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

Thanks Toker.  Now we can all call Apple, and when they tell us to take it in because it's a hardware problem, we can tell them about your experience.  For the rest of you, don't let them tell you it's a hardware problem...IT'S A LION PROBLEM.  None of us had the problem until we installed Lion.

Wow, that's rough Toker. I am right there with you, though my issue is slightly different. Still, I've been in and out of the Apple store more times than I care to admit. Please keep us posted with your issue! I too work in media and bought this iMac for work. It's pretty much been a $3k paperweight for me so far.

Slightly true, Marjean. I have only had Snow Leopard and also have freezing issues. I still haven't installed Lion.

My freezing problems on 2011 iMac turns out to be my belkin wifi.  If you are using wifi, try Ethernet cable instead.  Mine works fine now with cable and apple airport wifi.

This will most probably only be a solution for a minority here - I have never heard of a wifi router causing freezing in a computer so far. If it solves your problem, great! :-)

I have problems while running games, sometimes they run for hours without freezing (even if sleep was enabled in between sessions), then, all of a sudden they freeze, even two/three times in a row right after forcefully restarting.

Third-party RAM by the way (4GBB Apple + 8 GB Kingston).

Surym, what kind of freeze did you have? Is it where only the mouse moves, but you can't click on anything or make anything respond? Also, what exactly is made by Belkin? Your wifi router?

I've heard a rumor like this before, so I'm interested to hear more info. Unfortunately for me, my office is not near any ethernet ports so I am stuck with wifi. Seems strange that would be the issue, but anything is possible I guess.

Cantellolo, are you on 10.6 or 10.7?

10.7.2. The freezing in my case is mostly the kind where you can still move the mouse around and music keeps on playing while running a game.

Console messages at the time of the crash(es); mixed firefox and kernel messages:

http://pastebin.com/Ba5qCGhb

Yup, that's the same crash symptoms I get. From what I hear that's a operating system crash. Except I'm running 10.6.8.

I can't repro it 100%, but it always happens after the computer wakes from sleep. I'll have multiple Chrome/Safari tabs open and maybe some other apps, then I'll click something -- maybe an App Store link, maybe a program icon -- and I get the freeze.

I also get another occasional issue where I get popping out of the left audio channel, that also happens after sleep. Maybe I just need to disable sleep...

Sixteenbits,  the gray shade comes down when it freezes and I have to do a hard reboot.  It happens on 2 new iMac (Amazon gave me a replacement) and it's more frequent with Lion than Snow Leopard.  On Lion, I get freezes when the computer wakes up (try to connect to wifi) and video streaming. The problem is less frequent and more of a random cause with Snow Leopard.

I have spent a lot of time for the past 3 months doing everything recommended by Apple Care, including getting a new replacement iMac.  I finally took it to Apple store last week.  When Genius Bar couldn't replicate the problem, I figure it must be my wifi.  I use a Belkin router for my wifi.  Problems are solved now with either ethernet or my apple Airport wifi.

In my case, I am 100% sure it's the wifi.  I love my Lion now.

Sixteenbits, it's worth trying to turn-off the wifi just to test if it's the problem.  It does sound strange that OS wifi conflicts with certain routers.   I've spent so much time upgrading/downgrading OS, updating flash/java, run repair disk, resetting PRAM, etc. and the solution turns to to be so simple.  Good luck.

Those of us who don't use wifi still have the problem.

If it is indeed the 3rd party router, then the problem should be solved either by using Ethernet or an Apple wifi router. I don't have the ability to use the cable, but I do have an Airport Express. Perhaps I can try experimenting with using that router exclusively (I also have a Linksys).

Using Lion 10.7.2 on a late 2009 iMac. I've only had the freezing on video for about a week, even though I've had Lion for a couple of months. But, I just uninstalled MacFuse, and the freezing seems to have stopped. Annoyed to have to get rid of MacFuse.

I did that after noticing in kernel.log alot of activity with macFuse during the freezing.

I've just solved the problem, (at least on my iMac!)

My 27" iMac has just started showing the symptoms described.

I've had it a few weeks, preloaded with Lion and has been fine up until a couple of days ago. You Tube movies would cause everything to freeze except the mouse, like others here. It didn't happen after a full start-up, only when the computer had previously been asleep.

Because the problem had only just started I went back to a preference that I had only just recently changed.

Previously in System Preferences - Personal - General I had "Show Scroll Bars" set to "When Scrolling" and it worked fine. Changing that setting to "Always" seems to be the thing that caused the problem.

I've changed it back and it works fine again.

So, apologies if this has already been stated (I haven't been through all 85 pages!), to everyone who has this problem, (and unlikely as it sounds):

Go to System Preferences - General - Show Scroll Bars and set it to "When Scrolling".

Let's hear back if anyone else has success doing this.