Recently (maybe a month ago), Xubuntu 18.10 started freezing (hard freeze, no access to terminal, not even REISUB). The screen goes grey and if there was sound from the speakers, then there is a repeated short sound looping. I am forced to shut down the computer manually. These freezes happen at random, there is no pattern (even in clear desktop). There are times where days go by that this does not happen, and days where it happens twice in the same day.
I should mention that this is happening on two totally different computers of mine (one is laptop with Intel GPU, and another is a desktop with ATI GPU and a completely different CPU), so it is not hardware specific. There is nothing reported in /var/log/syslog during this freeze. I think that the most probable cause of these freezes is some recent update (probably kernel).
My questions: 1. Is anybody else getting such freezes? 2. Is there any way to troubleshoot this on my own? Should I look into some log?