Zone Alarm is a well known internet security package and most of the time it works fairly well. However, because this application has to sink its hooks deep into a Windows to protect the operating system, it can cause serious problems when the application does not uninstall correctly.
It seems, based off Zone Alarms official forums that there are a lot of people having trouble removing Zone Alarm and this is where the Zone Alarm Removal Tool comes in. Its a small, portable and freeware and its probably a good idea to have on your USB drive since you probably wont be able to connect to the internet to download it if you encounter these problems with Zone Alarm.
Thanks to rballard77 for recommending this one.