I have encountered this with several not so high end computers when loading something pops up the "Window not responding" window, but program is still running just fine.
Changing time out value fixes this issue and it should be by default at least 10 000 and not 5000. Maybe Zorin team could fix this in future updates?
You can change this value with dconf-editor
And navigate into: /org/gnome/mutter/check-alive-timeout
