Last night had 3 consecutive total freezes. The first one was out of nowhere, I was simply reading some RSS feeds on my newsboat program. Then, having heard that these freezes might be connected to having qubes os updates (either to the dom0 or to the domU’s) I have initiated the command line updates, using sudo qubesctl --show-output state.sls update.qubes-dom0 && sudo qubesctl --show-output --skip-dom0 --templates state.sls update.qubes-vm and pretty much a few seconds after pressing enter, I had another total system freeze. I had to press down on the power button to shut down the machine and restart qubes os. Then I repeated the same update command, and I had another freeze. At the third try, the update command went through without freezes and I saw that qubes os had downloaded updates to the whonix templates.
So, it indeed appears that these total system freezes are connected to fetching or downloading the updates. And perhaps doing these updates over the tor network? As I have my system download the system updates over Tor.
For the record, I am running vanilla QubesOS 4.1 with XFCE on a coreboot’ed Thinkpad X220 i5 CPU with 16 GB RAM.