OK. I reinstalled the "nouveau" driver and reproduced the bug. I was obliged to reboot the system because everything is frozen except the mouse cursor: no access to any terminal.
Then I typed in a terminal: $ sudo apt-get install xdiagnose $ sudo apt-get install python-apport $ apport-collect -p xorg 1453812 ERROR: Could not import module, is a package upgrade in progress? Error: No module named PyQt5.QtCore -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg in Ubuntu. https://bugs.launchpad.net/bugs/1453812 Title: System freeze when using LibreOffice Writer To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1453812/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp
