I'll try to tackle this, when u install ZoneAlarm and then uninstall guess what all the settings are still there...BUT I am not sure if ZA keeps certain files on your system that would prevent you from using another Firewall. My suggestion look at ZA's site, and go through program files, see if ZA folder still there, I'd say check Registery, but I dont want you messing with it and really messing up ur system, so stick to basic troubleshooting.