I understand that the ZoneALarm Removal Tool has been built into recent editions of ZoneAlarm products but it wasn't sufficient for me. I was having trouble with several ZoneAlarm Extreme features' not working correctly and was told to reinstall it.
Just reinstalling it didn't work for me. Too much of earlier installations was still left behind.
Even following the directions at Problem with anti-virus updates (http://forums.zonealarm.com/showpost...40&postcount=2) didn't work for me.
I iterated through the process described there and still had no success in reinstalling ZA Extreme (version 10.x) without problems. There were still remnants of older installations left.
Eventually after all that, I manually went through the Program Files directory and deleted the Checkpoint and ZoneAlarm folders I found there. I went through the Application Data folders for all Users in the Documents and Settings folder and deleted all Checkpoint and ZoneAlarm folders I found there.
I was convinced that no trace of ZoneAlarm would remain but I was wrong. Windows Security Center still knew enough to tell me that ZoneAlarm AntiVirus wasn't available. I have no idea where that info was recorded.
However, I must, finally, have eleted enough, to allow me to properly reinstall ZoneAlarm Extreme.
I hope this info is of some use to someone else.