iCal-Zimbra DST Sync problem

[dketchum]

I am in Arizona where we do not observe Daylight Savings Time. When I create a calendar event in iCal it shows up on the Zimbra server an hour early. When I create one on Zimbra it is fine in iCal. This is only 10.6.x (Snow Leopard) clients. 10.5.x clients do not have this issue. We have the Zimbra iSync connector (5.0.19_GA_3071) installed and have the checkbox selected for syncing calendars with CalDAV.

Zimbra version: 5.0.19_GA_3083 on Mac OS 10.4.11

I did open a Zimbra support ticket, 00051432 on 3/22/2010 but have gotten no response yet. I have contacted Apple (twice), but of course, they were unable to give me any in depth help, because of the 3rd party application (Zimbra)

Does anyone have any fixes or where to continue looking for a fix to this?
I have checked the time zone settings on the clients, server, and Zimbra multiple times and all appeared to be correct.