After uninstalling free Zone Alarm firewall, I notice registry fragments of the product still remain. Window's Defender even still thinks that it is the active firewall. When I attempt to delete any of the sub keys for Zone Labs in the registry under HKEY_CURRENT_USER/Software or HKEY_LOCAL_MACHINE/Software, I get the following
'Cannot delete registration : Error while deleting' . I'm running as administrator. and have set my permissions to full control for registry editing.
Any ideas on how I might remove these leftover entries ?

Operating System:Windows Vista Home Premium
Software Version:7.1 (Vista)
Product Name:ZoneAlarm (Free)