UM 21.10 Freeze

Specs:
UM 21.10 K: 5.13.0.27
HP i7 with Nvidia
updates: any new version

Since 2 weeks system gets to freeze randomly. In fact with 3-4 software active (e.g. TB, LibreOffice, FFox, ...) it seems they just stall one after the other - doesn't look like the first to freeze being the same all the times (hard to pin down). Can move the windows for a few seconds after that, but no clicking or writing allowed. Then the whole system freezes, i.e. no windows move, no menu or panel action.
Been waiting to see it coming back... no use. Have to reboot. Pages reopen where they were though (i.e. LO texts and web pages too)
In what log can I find answers ?

Thx for indications

W

What window manager are you using? I have a 21.10 VM that had an annoying freeze issue if I resized the VM window, and I finally managed to trace the problem to the Compiz window manager. If I switched to Marco, the problem did not occur. I opened a bug report, but got no replies, and finally tried resetting the Compiz settings to the default value, and that fixed the issue with Compiz.

So in short, if you are already running Marco, then unfortunately this will be of no help. If you are running Compiz, try switching to Marco to see if this eliminates the problem. If it does and you want to continue using Compiz, then reset the settings. Hope this helps.

With Marco already
My guess is that it may be related to when the laptop remains idle for a while. Still trying to figure out.
Merci

W