Comment 10 for bug 347848

I am having a similar issue, but I am not sure if its the same as other people here. My system seems to freeze mostly when using Mozilla Thunderbird, but that may be a red herring as I always have many other applications open. It just happened in Firefox while trying to watch a youtube video, and it happened last night while using the Youtube plugin for Totem.

This didn't seem to happen when I was using an Nvidia graphics card. The nvidia card was a PCI-E, now I am using a regular PCI Radeon card.

When the freeze occurs, the mouse still works, but no keyboard commands seem to work. I do have a USB keyboard though.

When I try to VNC into the frozen machine it doesn't work. When I ssh in, it works, but is very slow. When I check with the top command I see that the Xorg process is using a huge amount of CPU as if its caught in some infinite loop. So far no matter what I do, I have not been able to kill the Xorg process but my guess is that if I could kill it, I could restart it and get back into xwindows again (of course losing some of my current session).

When I ssh in, if I use the reboot command, something happens, I am not sure what. The ssh daemon seems to be shutdown as I can no longer ssh in, but the machine never reboots.

The only thing that works is to ssh in and do:
sudo shutdown now -h
If I do the above I can walk away and generally when I come back the machine is off and I feel good knowing that it shut down properly to some extent. I have never waited around to see how long it actually takes to shutdown from there.

In any case, this does seem like a major issue! I love ubuntu and want to get my clients, friends, family and associates to switch, but most people wouldn't accept and deal with a problem like this (the way I do).