Ubuntu freezes randomly

[700]

PROBLEM:
Ubuntu system freezes randomly.
Everything (except mouse cursor) gets frozen, including clock and keyboard (Caps Lock frozen, Num Lock frozen, tty terminal not available).

CONDITIONS:
- System: Ubuntu 18.04.1 LTS
- Machine: Dell Optiplex 990
- Processor: Intel Core i5-2400 CPU @ 3.10GHz × 4
- GPU: NV106
- GNOME: 3.28.2
- OS type: 32-bit
- CPU temperature: ~50C (OK)
- Syslog output:

Sep 7 23:17:01 ... CRON[6732]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Sep 7 23:25:15 ... kernel: [19122.475008] nouveau 0000:01:00.0: gr: TRAP ch 12 [003f672000 systemd-logind[795]]
Sep 7 23:25:15 ... kernel: [19122.475016] nouveau 0000:01:00.0: gr: GPC0/TPC0/TEX: 80000049
Sep 7 23:25:15 ... kernel: [19122.475024] nouveau 0000:01:00.0: fifo: read fault at 0000240000 engine 00 [GR] client 01 [GPC0/T1_0] reason 02 [PTE] on channel 12 [003f672000 systemd-logind[795]]
Sep 7 23:25:15 ... kernel: [19122.475031] nouveau 0000:01:00.0: fifo: channel 12: killed
Sep 7 23:25:15 ... kernel: [19122.475033] nouveau 0000:01:00.0: fifo: runlist 0: scheduled for recovery
Sep 7 23:25:15 ... kernel: [19122.475037] nouveau 0000:01:00.0: fifo: engine 0: scheduled for recovery
Sep 7 23:25:15 ... kernel: [19122.475042] nouveau 0000:01:00.0: systemd-logind[795]: channel 12 killed!
Sep 8 07:16:43 ... systemd-modules-load[286]: Inserted module 'lp'
Sep 8 07:16:43 ... systemd-modules-load[286]: Inserted module 'ppdev'
Sep 8 07:16:43 ... systemd[1]: Starting Flush Journal to Persistent Storage...

How to fix it, plz?

[ludapesi]

I'm looking for that issue also, I found this thread in the forum:
https://ubuntuforums.org/showthread....e-shell+killed

Maybe it solve the issue.

[3togo]

blacklist nouveau

https://linuxconfig.org/how-to-disab...c-beaver-linux