[System] How do you troubleshoot a freeze-up?

[Shibblet]

This has happened quite a few times on me now. Just a freeze-up in the middle of doing things... Mouse stopped moving, and I had no choice but to hard-boot the computer.
It's usually not a big deal, I just deal with it and move on... but now that it seems to be happening more frequently... and moreso, that I really don't even know how to begin to troubleshoot a "freeze-up."

[Qqmike]

Big, good question.
I'll drop kind of a standard list that comes to mind, until someone pipes in.

I've never tried this for a safe reboot:
Alt + SysRq (orPrint Screen) keys at same time, then one by one, slowly R -> E -> I -> S -> U -> B.

htop tells you your resource usage.

system logs: journalctl -b -1 -k

People often suspect system drivers, especially graphics drivers.

Hardware:

Is your PC overheating?
Clean out your PC case if there's a lot of dust.
Is it your power supply?
Is it a memory stick? Maybe use Memtest? (I've had this problem before -- a cracked module)
Is it a cracked motherboard? Jeez, I hope not, but I've seen that.

[oshunluvr]

First thing is to read log files. If nothing is being logged, then it's hardware.

Basically, note the time of the next freeze, after booting back up, read the output of dmesg and journalctl --since "1 hour ago" and look for segfaults, etc. If none exist, start looking at your hardware.

[kc1di]

in addition to what has already been mentioned check the cpu temp at the time of the freeze. if it's about 70c I would suspect that you need to clean the cool system. I've had this problem in the past.
Also If you running Nvidia graphics they can be troublesome at times depending on the driver, etc.
I usually install inxi which gives you many commands to check your system hardware and running conditions.

sudi apt install inxi

Then inxi -s will give you the cpu and mother board temps.
Good luck in sorting it out.