My system keeps freezing

Today already, in the past hour, my system has froze on me several times. What happens is that I can't click on anything to get it to open. I can move the mouse over something and click - nothing happens.

I did a clean re-install of Ubuntu 22.x lts less than a month ago. I don't know what's going on. My only way to escape it is to do a shift+print screen+reisub

Any ideas what's happening ? I've used Ubuntu for years and haven't had this problem before.