SyncServices (iPhone-iCal) and Outlook-iCal sync work again after removing multiple calendar events
I have had increasing problems for some time with Sync Services (iPhone to iCal) and Outlook to iCal, which were both getting slower and even incomplete (posts were missing or not updated). The Sync Services process would sometimes use almost the entire processor capacity, making the whole computer slowing down and the fan working really hard to cool down the processor. Adding a cooling fan tablet underneath solved the heat problem, but not the underlying problem :-)
I went through all steps recommended in this Apple KB article (http://support.apple.com/kb/TS2481) and things became slightly better after reset etcetera, but were still not satisfactory.
I then searched and found more than 25 000 calendar event instances (in the time frame 2005-2008). Most of these were repeated between 5-10 times, but a few occured 100:s times and two events even 1300 times! After removing all of these multiple instances (which took me about 5 hours using the search-and-delete function), the machine is quicker than ever before and the syncing functions work quickly and accurately in both directions, from iPhone to iCal and from iCal to MS Outlook or the other way around. I also used the Replace all content on iPhone with iCal when I syncronized the iPhone to avoid everything to be copied back again. One particular problem was all calendar appointments, that forces updates to be mailed to all invited parties when I deleted the event - I just turned the machine into offline mode and removed all outbox content of the Outlook mail services before turning it on-line again.
I can imagine this multiple instances problem stems from disorder in the sync registry, such that the same event is taken for a new one and copied back and forth. Particularly the repeated events as birthdays etc took a lot to get rid of. I now recall Sync Services has prompted me, after resetting the sync history, to resolve mismatchs between MS Outlook and iCal (I was asked to tell which posts should be kept), but there was no difference between these posts.
This problem could be resolved by a new function that stops the same event to occur more than once on the same day, or even simpler, just add a PURGE function to iCal and Outlook that allows all events older than xx days to be removed entirely (possibly first reminding the user to write the calendar content to a PDF-file in case one wants to trace back in time). The same would then hold in the Sync Services, give the user the option to avoid syncing of old objects. For some reason, I doubt the option given in iTunes to avoid old objects did work accurately in my case but I am not sure.
It would be interesting to get comments from Apple as well as the MS Outlook team on this issue, because it took me quite some time to find out and I found only one hint in a forum that pointed on the multiple calendar event problem. It could be pointed out clearer I think.