debian freezing

[Pierre Frenkiel <pierre.frenkiel@gmail.com>]

Since I installed Debian11, it happens from time to time (generally when 
I leave the system unattended), that everything freezes:

keyboard and mouse.

I found on several blogs some silly recommendations, involving typing 
something. I say "silly" because in that case in I can't do anything:

neither with the keyboard nor the mouse

when I say "frozen" it means "frozen" (may-be "dead" would be a better 
word, as the computer doesn't answer to ping)

and the only thing I can do is reboot, being after that obliged to 
re-install.

I tried running the screensaver,but the problem remained.

Has anybody a solution?

Thanks in advance

Best regards

Pierre Frenkiel