Session randomly closes

[alexsid]

Hi everybody!
I experience a strange event. Sometimes, randomly, when I work or when my computer is idle, the session closes, all apps closes, and I see the Siduction login screen. I have to start a new session, reopen apps and so on. I cannot understand the reason. I use a tabletop PC. My computer is 10 years old, 4 cores Intel CPU, AMD GPU, 24 Gb of RAM. What might be the reason of unexpected session closure?

[eriefisher]

Is there anything in the journal? It should post the event. Is this with X or wayland?

[alexsid]

It is X11 session.

I don't know what, where and how to search in the journal

[eriefisher]

Check /home/$USER/.xsession-errors to start. Maybe .xsession-errors.old. Might show a crash.
journalctl -b -1 should give you the previous boot.