On an XP box with Activesync 4.1, Outlook 2003 SP2+all current patches, Win Mobile 2003, for all intents and purposes you can only sync the calendar out from Zimbra, not in from PDA. It's interesting, in that it will sync a single appointment or change from the PDA, but if there has been more than one change/add/delete on the pda, the remaining items will come back unresolved from Activesync w/ error 80180E01. This is with Outlook closed. If you sync with Outlook open, and are unfortunate enough that Activesync actually works, you get the new items on your calendar, but Outlook crashes the next time it tries to sync with Zimbra. Reopening outlook results in continuous crashes of Outlook upon the sync with Zimbra. The only solution is to delete the MAPI profile and start over, which leads you back to the top of this email, and back down the same destructive path. I have done a hard reset on the PDA, and tested on multiple xp boxes (including a clean XP install) with the same result, so I know it's not something special with my machines. I tried to use the sysinternals debug logger, but I don't get any messages. Any help or suggestions would be greatly appreciated.