The random and frequent freezes occurred two days ago after a system update (I don’t know what exactly was updated).
After the system update, the settings did not show up. I then checked the driver used - it was Nouveau. So I used ‘Software & Updates’ to switch to nvidia-driver-470. (But it turned out that the driver had nothing to do with settings disappearing. It was solved by reinstalling another ubuntu package.)
Before this, even under heavy load, the system would not freeze and only the fan would spin very fast. But now it freezes at login or freezes when I open a terminal or click on some applications after a fresh login when no other processes are running. The keyboard and mouse stop to respond and hard shutdown is the only way to get out of the situation. For the last days, it has occurred 4 or 5 times per day, without any earlier signals.
Ubuntu 18.04 Dual boot. My generic kernel is 4.15.0-151-generic .
Lenovo Thinkpad P51 with:
graphics: Quadro M1200/PCIe/SSE2
recommended driver: nvidia-driver-470
Attached pls find the bug report. Many thanks in advance for your help!
nvidia-bug-report.log.gz (1.2 MB)