Picked this up elsewhere thought it was worth sharing.
http://download.zonealarm.com/bin/fr...cessIssue.html
Workaround to Sudden Loss of Internet Access Problem
Date Published : 8 July 2008
Date Last Revised : 9 July 2008
Overview : Microsoft Update KB951748 is known to cause loss of internet access for ZoneAlarm users on Windows XP/2000. Windows Vista users are not affected.
Impact : Sudden loss of internet access
Platforms Affected : ZoneAlarm Free, ZoneAlarm Pro, ZoneAlarm AntiVirus, ZoneAlarm Anti-Spyware, and ZoneAlarm Security Suite