I have a mixture of old and new which isn't working. The new: I recently upgraded my software firewall to ZoneAlarm Extreme Security (I had been running ZoneAlarm Security Suite for the past four years). The old: I have a 2003-vintage Dell Axim X5 PDA which syncs with my Outlook databases via Microsoft ActiveSync 3.8.0 (I believe this is the latest version which will work with the X5). Ever since I upgraded to Extreme Security, ActiveSync will connect my PDA to my Dell desktop (running under Windows XP Professional SP3), but will not sync the databases. In ZoneAlarm, I have set the Trust Level of both ActiveSync Application and ActiveSync Connection Manager to "Super."
Later: I think I just solved the problem: I did a "soft reset" on the PDA, and suddenly it resynced with my desktop. This is only the second time in nearly six years that I have had to use the reset button on this PDA. I will go ahead and post this "query" for the benefit of others who might encounter similar problems, even though I have already solved it for myself.