random freezing in macos 10.13.6
lately i've been experiencing macOS unexpectedly freezing without any way to bring up activity monitor or recover.
do not know why, as i have not installed any recent new software .... the only new software that i get is updates for office 2016, and I regularly use CCleaner to flush out caches and other useless files.
if there is a way to find out what's causing this, i'd like to know if anyone can help. first i'd like to try troubleshooting methods before resorting to something more drastic like reinstalling macOS ....
thank you
macOS High Sierra (10.13), 2.0 GHz/16GB/256GB