I often found that Ctrl+Alt+Delete unhangs the Windows PC. I googled why?

The nutshell answer is : Ctrl+Alt+Delete is a secure attention sequence (SAS) triggers a system interrupt, effectively forcing the computer to respond. This is directly handled by the Windows operating system kernel. That means it can bypass most of the stuff that’s currently running (including frozen apps or even some parts of the graphical interface).

Cool to know this.