Comment 16 for bug 103603

This appears to be identical to bug 120347.

I'm running Kubuntu Feisty and I have an nvidia geforce 6200. I encounter the exact same problem: after leaving the computer running over night, I come back and xorg is at 100% (on one of my CPUs) and the window decorations have disappeared. Since I have a dual CPU system, my guess is that it is more tolerant towards this, so although X is completely frozen (only the mouse moves), I can ctrl+alt+F1 to a console and take down the system cleanly. (however, if I switch back to the X server before rebooting, the window decorations are gone)

After a reboot everything is fine. I also ran strace on xorg when it goes berserk, but the only thing that was noteworthy that I came up with was also the SIGALRT message. Comparing it to an strace of xorg in normal conditions (when it's not going berserk), however, revealed that the SIGALRT message also comes up during normal operation, and neither that nor any other calls that xorg makes while it's berserk indicate anything out of the ordinary.

Further, I have taken advantage of the dual CPUs to examine all logs in detail as the problem occurs: nothing out of the ordinary, in fact, since the system has been sitting idle, hardly any activity is logged. I checked the KDE settings and they are showing the screen saver to be off. I do have kpowermanager installed (because I had a problem where my network card would stop working after a while otherwise), but it's set to "Performance" and the screen saver, auto-suspend for the screen, and in fact all other power-saving options are unchecked. My screens do turn blank, however, after a period of inactivity, so it's possible that this is related.
On a side note, I have three monitors on two nvidia cards, running on xinerama with the 9755 nvidia binary drivers. All signs point to this not being a driver problem, however, unless nvidia and intel use some of the same libraries in their drivers.

I also wanted to point out that I usually don't lock my screen when I leave, so that might not be relevant to this particular problem.

In addition, my GLX does not work for some reason. Whenever I try to run a glx-enabled app, the app crashes, although it is installed, because the glxinfo command outputs a grid with the glx info.
Zoltan, please let me know the status of your GLX (try running a GLX screensaver and see what happens), as well as any power management software (such as kpowersave) that you may have running on your system. Also, do you have a screen save enabled and do your screens go into auto-suspend mode after a period of inactivity?

This is a really tricky problem and I really have to find a solution because it's starting to happen even after shorter periods of inactivity. The intervals are seemingly random, making the problem virtually impossible to reproduce and difficult to troubleshoot, but usually the problem happens after long periods of idle time (although it has occurred after only a few minutes of idle time), and every time it happens my workflow is interrupted, so it's really starting to bother me. It's also embarrassing if you're about to show someone (i.e. a client) something on your computer and it's completely frozen. If we put our notes together, we will probably be able to resolve the problem a lot quicker.