I had the same problem in Ubuntu 18.04.1 with latest Updates to now, Gnome 3.28.2, 64 Bit System.
Problem:
Preview of ODT-File lets freeze the whole desktop suddenly (suddenly fan begins to rotate hearable), but nothing works (at least with Ctrl+Alt+F3 I could switch to console and after login as user (no sudo!) I could reboot without problems).
I had the same problem in Ubuntu 18.04.1 with latest Updates to now, Gnome 3.28.2, 64 Bit System.
Problem:
Preview of ODT-File lets freeze the whole desktop suddenly (suddenly fan begins to rotate hearable), but nothing works (at least with Ctrl+Alt+F3 I could switch to console and after login as user (no sudo!) I could reboot without problems).
Solution: /bugs.launchpad .net/ubuntu/ +source/ gnome-sushi/ +bug/1739893/ comments/ 4 ) of "Daniel (2-ubuntuone-4)" and tried his suggustion to install unoconv. Now I am able to preview ODT-files without freezing the X-Server.
I searched for a possible solution. Then I read #4 ( https:/
last but not least: Thank you!