Debian Stretch freezes often

[Enzo Guerra <enzo_guerra@gmx.com>]

hello
having problem with Debian Stretch 
(installed around Mar 15, 2019, by netinstall)
it is freezing quite often
seems random while using different programs
my system:
Ryzen 5, 16gb, ASUS 320 motherboard, mp500 m.2 120gb ssd, debian on
complete disk (1 partition, also a swap partition), used uefi and lvm
have an amd rx560 gpu, installed non-free amdgpu driver
typically installed software (libs) with aptitude
aptitude reports no broken packages
did install GOG game BG2EE with instructions 
from https://wiki.dotslashplay.it/en/games/baldurs-gate-2
game plays okay, but freezes also
other programs i run:
gedit, make, g++-6, vim, evolution and iceweasel
not sure what information i can provide to help solve this problem
please let me know
regards
enzo