How can I investigate the cause of total hang? Is there some information that I should pay attention to in order to get some hint?

[Karl Auer]

On Sat, 2020-07-04 at 06:43 -0600, Drew Einhorn wrote:
> I'm using my computer.
> I walk away come back later.
> It is now unresponsive

Coming in late, so forgive me if this has been said.

Is the "unresponsive system" actually asleep when you return to it?
Does your system show some clear indication when it is asleep (or
hibernating)? If NOT, try disabling all automatic sleeping hibernating
and blanking, and see whether the system still becomes unresponsive
after you walk away for a while. You could also inspect the sleep/blank
settings and just wait that long to see if it happens "on time" :-)

Not coming back from sleep and not coming back from blanking are (or at
least used to be) relatively common problems, though sadly not with
common solutions. If you can show conclusively that the issue is
related to sleeping, hibernating or blanking, you will at least have a
better idea where to look, and also a good workaround (disabling them).

Did this problem develop recently or has it always been there on this
computer?

You *may* be able to restore graphics without actually restarting the
computer, by just restarting the display manager. When logged in, look
in the process list for something with a name like "gdm" or "lightdm"
etc. Then try restarting that process. For example, if you find gdm3,
you might restart it with "systemctl restart gdm3". You could also try
just killing the process, as it will generally be restarted
automatically, but I have not tried that myself.

Regards, K.

-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Karl Auer (kauer at biplane.com.au)
http://www.biplane.com.au/kauer
http://twitter.com/kauer389

GPG fingerprint: 2561 E9EC D868 E73C 8AF1 49CF EE50 4B1D CCA1 5170
Old fingerprint: 8D08 9CAA 649A AFEF E862 062A 2E97 42D4 A2A0 616D