Conflict with Zone Alarm
Zone Alarm was already a suspect for causing a conflict, seems to be dependent on the order in which things load. As you mentioned 2000 is getting quite old and is is becoming increasingly difficult to find compatible applications. I will be doing a look for other free firewalls, but eventually I plan to build a Windows 7 machine to replace this one. I have Avast on a Windows 7 net book and it seems rock solid. My decision to use it there was based on it being one of the last to support Windows 2000 and the combination of low system resource use and good protection and tune-ability.