Please open ZoneAlarm by going to the Windows START menu, Programs, ZoneAlarm and choose ZoneAlarm Security. When it opens go to the AntiVirus/AntiSpyware option on the left and click “Update Now” to bring the definitions up to date.
Now click the Advanced Options button and then the Updates button and make sure that the options to Enable automatic updates are ticked.

Also go to Overview on the left and then Preferences and click Check For Update.

ZoneAlarm will update itself at regular intervals but this process will force it to instantly update itself.