It's possible something related to the screen crashed. Next time the problem occurs please look in /var/crash and tell us if you find anything.
Please also (after any future hang) reboot and then run: journalctl -b-1 > prevboot.txt and attach the file 'prevboot.txt' to this bug. ** Package changed: xorg (Ubuntu) => xorg-server (Ubuntu) ** Also affects: unity (Ubuntu) Importance: Undecided Status: New ** Also affects: compiz (Ubuntu) Importance: Undecided Status: New ** Changed in: compiz (Ubuntu) Status: New => Incomplete ** Changed in: unity (Ubuntu) Status: New => Incomplete ** Changed in: xorg-server (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of compiz packagers, which is subscribed to compiz in Ubuntu. https://bugs.launchpad.net/bugs/1853707 Title: Whose system stopped responding because of single program's fault - no way out, had to force power off To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/compiz/+bug/1853707/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~compiz Post to : compiz@lists.launchpad.net Unsubscribe : https://launchpad.net/~compiz More help : https://help.launchpad.net/ListHelp