ICal Syncs From Exchange, but not To Exchange -- funky Console error.

Question

I'm the IT guy troubleshooting a user's MacBook Pro 15" (not unibody) with Snow Leopard. The Mac users in my company have been having near-constant trouble with their email and calendars almost since the day they switched, first with Exchange 2003/Entourage and now with Exchange 2007/Snow Leopard (guess how I feel about those "Enterprise Ready" ads!) -- random show-stopping issues like this have plagued them and I delete and resync something almost weekly. (By comparison, the hundreds of Outlook users on my server have never needed to delete and resync. Blackberry users occasionally, iPhone/WinMo users almost never.)
Calendar items in iCal don't get synced up to my Exchange 2007 server, however creating an item in Outlook Web Access (i.e. directly on the server) get synced down to iCal just fine. I've tried refreshing, etc.
In Console, there are repeated error messages saying "save failed" ... "Items cannot be deleted from alarms." Unfortunately it seems I'm the first person known to Google to have this error (yay!) hence the post here. Your advice in resolving the issue is appreciated because I'd rather not wipe his iCal and resync from Exchange, given that an unknown number of appointments haven't yet synced up to the server and thus data would be lost.
Below is the full error message from Console, which repeats once every minute. The only differences between errors are the UserInfo which appears to increment. The appointment in question, "Call Adam Hird" from 9:00 to 9:15 on 11/19/09, looks fine in iCal except that it appears to have been renamed "Call with Adam Hird" with a location (a 10-digit phone number with hyphens) added (which iCal might not like, since the appointment name is just followed by a long dash "--" and nothing. Removing this doesn't appear to solve anything.) and the time changed to 9:00-9:30. It doesn't appear to fix itself when I change its time to 10:00 (again I don't want to delete anything since that might "fix" the problem without actually solving it.)
11/20/09 10:34:45 AM iCal[45688] save failed: Error Domain=NSCocoaErrorDomain Code=1600 UserInfo=0x105b79590 "Items cannot be deleted from alarms." {
NSLocalizedDescription = "Items cannot be deleted from alarms.";
NSValidationErrorKey = alarms;
NSValidationErrorObject = "<CalManagedEvent: 0x11648ac00> (entity: Event; id: 0x116bb9f60 <x-coredata://A9655919-B156-400F-A34C-EF02353540AF/Event/p4310> ; data: {\n alarms = (\n \"0x1167ea520 <x-coredata://A9655919-B156-400F-A34C-EF02353540AF/Alarm/p615>\"\n );\n attachments = (\n );\n attendeeComments = (\n );\n attendees = (\n );\n calendar = nil;\n calendarServerAccess = nil;\n changeKey = \"DwAAABYAAADEcN5FDQgWT5LycXCBLbcoAAETZn/9\";\n classification = 0;\n creationDate = nil;\n dateStamp = \"2009-11-19 08:06:16 -0700\";\n deleteSyncRecord = 0;\n dontSchedule = 0;\n dropBoxFreeBytes = nil;\n dropBoxLocation = nil;\n endDate = \"2009-11-19 09:15:00 -0700\";\n hasAlarm = 1;\n hasAttachment = 0;\n hasAttendee = 0;\n hasDropBox = 0;\n hasRecurrenceException = 0;\n isAllDay = 0;\n isDetached = 0;\n isInvitationDirty = 1;\n isInvitationSent = 0;\n isMyResponseDirty = 0;\n isPhantom = 0;\n isRSVPNeeded = 0;\n itemID = AQMkADcwMjFkMGM4LTZlYmMtNDM3Mi04OWYwLTM4ZDRjZDQzZD;\n localUID = \"local_74189D19-882A-4BE1-BC99-86D1E796245B\";\n location = nil;\n masterException = nil;\n messages = (\n );\n needsReply = 0;\n needsServerConfirmation = 0;\n notes = nil;\n omitSyncRecord = 0;\n organizerAddress = nil;\n organizerAddressString = nil;\n organizerCommonName = nil;\n permission = 3;\n privateComment = nil;\n recurrenceEndDate = nil;\n recurrenceExceptions = (\n );\n recurrenceRule = nil;\n sequence = 0;\n sharedUID = \"C33E682B-8DB1-436B-98B2-11F69E069E69\";\n startDate = \"2009-11-19 09:00:00 -0700\";\n status = 0;\n timeZone = \"US/Mountain\";\n title = \"Call Adam Hird\";\n transparency = 0;\n url = nil;\n urlString = nil;\n})";
NSValidationErrorValue = "Relationship objects for {(\n <CalManagedAlarm: 0x1039b3890> (entity: Alarm; id: 0x1167ea520 <x-coredata://A9655919-B156-400F-A34C-EF02353540AF/Alarm/p615> ; data: <fault>)\n)} on (<NSRelationshipDescription: 0x114aaad40>), name alarms, isOptional 1, isTransient 0, entity Event, renamingIdentifier alarms, validation predicates (\n), warnings (\n), versionHashModifier (null), destination entity Alarm, inverseRelationship item, minCount 0, maxCount 0";
}

Answer 1

Despite my reservations, the user needed his calendar to sync ASAP, so I deleted the Adam Hird appointment. Then I thought "might be a good idea to back it up so I can help Apple Discussions troubleshoot!" so I pressed Cmd+Z to undo the deletion. Apparently this unstuck the clog-- the test appointments that weren't syncing up to Exchange deleted themselves (oops) and the Adam Hird appointment reverted back to its Exchange state (9:00-9:15, no location). Further tests show that syncing now works fine with no Console errors.
Any ideas? Consider this a bug report, I guess...