My system seems to crash from time to time. I still don’t know what causes it.
If I leave it untouched for a few hours, sometimes, it crashes.
To resume, I have to force a reboot by unplugging the power cable (not even pressing the power button for N seconds seems to work).
Then, it seems to work just fine (after displaying some error messages about lost or orphaned inodes at boot). Until, one day, it happens again. When? I never know. It seems to follow some strange and unpredictable pattern.
Where should I start investigating?
Only when it’s idle for a while? That would point to power saving or suspend. You could try changing those to see if it affects the situation.
But yes, hardware. And I would suspect the display controller in particular. I’ve seen many that glitch when in power saving.
Also, have you checked for bios updates?