Comodo Firewall Pro only "pops up" if the status quo is about to be changed for some reason (i.e. installing new software or a notable file/folder change).
Better to be warned rather than sorry afterwards..:-)
I've been using Comodo for a couple of months now after many years with ZA and am very happy with its performance.
Likewise, I've recently started using Comodo Registry Cleaner (freeware) which I've found equally efficient.