[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.