desktop mysteriously freezes until keyboard or mouse input

Thank you for taking the time to report this bug and helping to make Ubuntu better. Please attach your X server configuration file (/etc/X11/xorg.conf) if it is exists and X server log file (/var/log/Xorg.0.log) to the bug report as individual uncompressed file attachments using the "Attachment:" box below. Could you please also try to run without any /etc/X11/xorg.conf and let Xorg autodetect your display and video card? When you do please also attach the /var/log/Xorg.0.log from this attempt. Thanks in advance.

When you experience the freezing on your pc, could you also attach the kern.log and sys.log to this report.

I attached four log files. I notice many rtkit-daemon error messages in syslog. The process 1962 mentioned in those error messages at the very bottom of syslog is a pulseaudio process.

Also note, I upgraded to Ubuntu 10.10 today but I still see the issue. I believe the system is now using the proprietary 10.8 Catalyst driver included with Ubuntu.

Same issue on my side. Just bought a new laptop: Lenovo G550, installed Ubuntu 10.10 and am facing issue as above: while it is not all the times, it very often (50% of time?) runs into mode where until I move mouse or press a key the computer completely freezes (does completely nothing, e.g. flash animation on the web stops, or screensaver demo). It does things in the background only as long as I am moving the mouse.

Interesting: this laptop model is known for its issues with touchpad. In my case, when I use touchpad, every few minutes touchpad stops working for approx 5 seconds and then it works again.

Visual effects linkage: not sure if any. E.g. I was using "normal" visual effects mode when the system freezing started. When switched to no visual effects in Ubuntu, the freezing continued.

I do not have xorg.conf on my fresh Ubuntu 10.10.

Hmm, weird, let's troubleshoot it as a driver issue, although I suspect kernel or something else.

I did more testing on my box. With the box in an idle state (~0% CPU load), I used a hitch-detection script (it prints a "hitch" error to stdout every time the system goes more than two seconds without scheduling the script) to try the following:

After sudo /etc/init.d/gdm stop, and logging in at the text console (ctrl-alt-F1), the script still reported hitches, so the issue would not seem to be X-related.

Still on the text console, /etc/init.d stopping apache2, ntop, mysql, ntpd, had no effect, I still saw hitches.

Switching into single-user mode (sudo telinit 1, choose without networking) had no effect, I still saw hitches.

During a hitch, tapping the ctrl key was enough to immediately wake the system back up (causing the hitch to be reported by the script).

After restarting gdm, I tried uninstalling Sun VirtualBox, but I still saw hitches.

I found an old Ubuntu 9.10 CD and booted up from that. No hitches detected after 30 minutes.

Resetting the BIOS/CMOS (by selecting "Load Optimized Defaults") appears to have fixed this issue. 5 hours so far with no hitches (freezes). I can't imagine why any BIOS setting would cause this issue with Ubuntu but I'm optimistic about the problem being fixed.

IIRC this box is 16 months old. The only BIOS options I clearly remember tweaking were the boot order and some enable-virtualization setting. I'll continue testing for a few days and see if I can isolate a single setting that causes the issue.

Status changed to 'Confirmed' because the bug affects multiple users.

I had a similar effect on an AMILO Pi 2550 (Intel T8100 Core 2 Duo processor). The problem was not related to X, but seems to be caused by problems associated with deeper sleep states of the processors (BIOS bug?). Adding "processor.max_cstate=1" to the kernel boot parameters solved the issue.