Take mind this may not be your problem, but for me one of the files that is updated in the system32\zonelabs folder was corrupted. I was able to fix my problem then by uninstalling, renaming the folder from "zonelabs" to "corruptedzonelabs" forced the clean instal to recreat a new zonelabs folder, and successfuly update.
*I could not remove the corrupted file but the rename of the parent folder still worked.
Operating System:Windows XP Home Edition
Product Name:ZoneAlarm Internet Security Suite