You want to know if K9 Web Protection has compatibility issues with other security products.
K9 Web Protection is compatible with desktop firewalls (e.g., ComputerAssociates ezArmour, McAfee Desktop Firewall, ZoneLabs ZoneAlarm, etc.) as long as these firewalls are set up to allow K9 to access the Internet.
If you are using a desktop firewall, you may be prompted to allow k9filter.exe access through the firewall during the installation. Please consult your desktop firewall documentation for instructions on how to enable k9filter.exe to access the Internet.