MacOS – How to force quit the “Force Quit Applications” window

The Force Quit window usually freezes when the system is paging heavily. (Same with the Dock.) Your computer could probably do with more RAM.

You can move windows around when they're frozen because OS X's window manager isn't frozen, and it controls basic window functions like minimize and move.

Sounds as if you may have run your system out of RAM, which is quite possible with the anemic Air designs Apple is passing off as computers these days.

you may well need to do a hard shut-down and reboot.. hold down power button till it shuts off, then wait 5-10 seconds and reboot.

If terminal does the same thing after that, then you may have an actual issue..