New PC [Machine # 1] and newly installed Leap 15.0 [2 - 3 weeks] using an WD SN750 250GB nvme m.2 for the 1st time [btrfs]

Machine not used for anything heavy, no gaming or video editing.

May have 6 or 7 file [Dolphin] windows open.
Running chrome with 2 or 3 tabs open
Music player [Clementine] running
Solitaire game [KPat] running.

All of a sudden the desktop will freeze and while waiting a bit to see if it will clear itself , the PC reboots itself.
This all occurs within a minute from the time it freezes until the reboot happens.
I am not doing anything in particular when this occurs, maybe reading an email or using facebook or starting a program [Audacity,
Leafpad, etc.]

I have read a few posts about desktop freezing in in Plasma in Leap 15.0, but not the reboot that my PC does.

What might I check for my nvme ssd to see if that might be a problem? [proper setup for btrfs, etc.]
1st time for me for btfrs and 1st time for nvme.

In /var/log which log might tell me something about what is happening?
I have looked at some of them, but am not really understanding what they say.

Would running "journalctl -f" tell me anything.
How would I get the results from "journalctl -f" after the machine has rebooted?

These are all guesses from the other posts I have read , but again none of the other posts mention a reboot occuring within their problem.
What other information/tests can I provide to solve this problem?

Thank You