I am not aware of any change in servers used but you need to check if you are actually downloading any files from the server. If not, its more an issue of non updating IP cache (i.e. you are contacting a server that is not anymore ZA).
Update system will radically change in version 9 also to facalitate dial-up users. You may want to try the new ZA Antivirus 9 beta (www.zonealarm.com/beta) to see if you have the same problem.