Well that's just because it really works perfectly on some systems... just like on my wife's computer. It was working perfectly on mine too, it's just I decided to try latest version of Kerio Firewall (even though it's being discontinued).
There must be some catch, something must be wrong deep inside the code I guess. Also, maybe it's computer configuration sensitive and it shouldn't be... you still need to wait for an answer from ZoneLabs since it looks like on many machines ZA works just fine along with avast!
Truth is, there are some issues with ZA latest version, and if it's not true, we wouldn't have so many people reporting this problem. So, someone realy needs to do something regarding this...