I attempted to install the new ZoneAlarm Pro 4.0 (upgrade) multiple times -- and then also attempted to RE-install the old version 3.7.159, multiple times -- a total of eight or ten times, before I could get Zone Alarm working again. It had been working fine before the 4.0 upgrade. The problem ? The DiamondCS WormGuard totally prevents a successful install of ZoneAlarm (either version 3.7 or 4.0). The cause of the problem was eventually determined using the Filemon utility from - www.sysinternals.com -- <http://www.sysinternals.com/ntw2k/source/filemon.shtml>. I'd suggest that both DiamondCS and Zonelabs should warn their customers to turn off (remove) WormGuard protection before installing or updating Zone Alarm. Someone at DiamondCS might want to verify this WormGuard behavior, and then alert Zonelabs -- to save customers some real headaches. Bill K.