Q: Why does my entire system freeze when I watch YouTube after Lion install?

Just to add my report: 2011 iMac 27'', Lion, watching a movie (quicktime, itunes, browser, whatever) often results in total freeze of the system. mouse still works but have to restart using power button.

Please please please apple look at this. Is there any better way to escalate this problem?

just to update my progress:  i didnt have java installed at all, when i went to java preferences, it advised me to install java.  i installed v 1.6, clicked the button referenced earlier "enable applet plug-in..."  restarted the browser and have been yet to crash my imac.  i even had apple trailers and youtube running in multiple instances on multiple desktops, and have slept and awoken my imac many times.

this seems to have solved it for me.

**redacted - - next video i clicked on froze it**

same error in console everytime:

7/21/11 8:08:49.000 PM kernel: ** Device in slot: SLOT--1 **

7/21/11 8:08:49.000 PM kernel: ** GPU Debug Info Start **

7/21/11 8:08:49.000 PM kernel: 0x00006740

and then a huge string of debug characters

Same issue for me as well. 2011 iMac running Lion, freezes when going on YouTube, unable to force quit out of Safari.

FWIW, it doesn't seen to matter what browser you use. They all seem to do the same thing.

I was wondering if all you guys are using Screen Sharing? I disabled it and I didn't have the hang until now. But I might by cheering to early

Yes, I'm using screen sharing. I have disabled it now to see if that helps

So far so good.

Let me add another "me too" to this. I have a brand new (as of July 7) 21.5" iMac. I upgraded to Lion. So far I have had the video playback problem on Amazon (trying to view a product video), YouTube and on Flickr (trying to view a member submitted video). In all cases the the system froze and the only thing that seemed to work was the ability to move the mouse pointer via the mouse (although moving the pointer around had no other effect). I had no option but to hold down the power button until it powered down.

Not that it is related to the same problem (as far as I know) but I also couldn't get Netflix instant play to work on Safari (although it works fine on Chrome).

Yet another "me too" on this issue.  Total freeze when playing video, still hear sound, can still move mouse. Brand new 27" 2011 iMac running Lion.  I did not notice this at all prior to Lion upgrade.

I've only been able to reproduce it when resuming from sleep, never from a cold boot.  Yet to test youtube, but happens with video from iTunes and iPhoto.

There is a similar thread here: https://discussions.apple.com/message/15676049#15676049

I have the same issue (iMac 2011 27" i5) with Lion. Hope an update will solve the problem soon

Same problem here, very annoying. 27inch iMac, i5.

Freezes on all browsers.

Can move mouse and hear audio from itunes, but cannot interact with anything in the operating system.

Reinstalled flash after 10.7 upgrade, no help.

Wish I did not upgrade

Same machine (27" iMac i7 8G 2T) bought one month ago.  Updated to current flash player and Java for LIon yesterday.  I managed to catch the freeze coming this morning and force quit Safari.  The machine froze when restarting Safari.  It dies upon launching video... so far mainly embedded YouTube.  Common factor every time is that iTunes was running, and continued to play while everything else froze (funny seeing a dock icon suspended mid-bounce).  No problems prior to Lion upgrade. 

After disabling I didn't have the hang anymore. My uptime is now 1 day, 22:12. Before I got this hang several times a day. Did anybody see this hang when they _didn't_ have screen sharing enabled ?

I have the same problem on my 2011 baseline 21.5 iMac.

No screen sharing and freezing persists.