And here it is:
I have been having one headache after another with syncing my MacBook to my new Curve 8310. After days and days of research, I *finally* found some information that allows you to get to the root of the problem, namely Sync Services.
A little history/background for those of you who like to understand what you're doing before you do it: Sync Services is what Entourage uses to talk to iCal and Address Book, and apparently iSync is eliminated from this communication. Sync Services has a "master" database in which all information from Entourage, iCal, Address Book (and any other applications you may be using to sync PIM data) is aggregated.
If the communication with the master database (which Mac calls the "Truth Database") becomes convoluted, you will not be able to sync properly (or at all) between Entourage and iCal. Incidentally, if you can't sync Entourage to iCal, you won't be able to sync to your Blackberry, either, because the Blackberry apparently pulls it's information from the iCal database. (If this is incorrect, please, someone correct me.)
There are instructions here in the Missing Sync forums on how to use the "Reset Sync History" button in iSync to attempt to reset communications with the master database; however, this doesn't seem to remove all of the pieces of the puzzle that are gumming up the works. BUT ... and this is going to be *very* exciting to some of you who have been banging your heads against the wall like I have ... there are instructions that will get to the heart of the problem, and you can find them here on The Entourage Help Page:
Troubleshoot Sync Services (select option #2 to learn how to reset syncing)
**** PLEASE BACK UP YOUR DATA BEFORE DOING ANYTHING ****
The process outlined in the link above will delete all of the data in the master database, and optionally, your iCal and Address Book data
In my situation, Entourage is my primary database. So, I used the Archive function of Entourage (via the File/Export... menu item) to back up each category of data individually (i.e., calendar, contacts, tasks and notes). If you have a clean copy of your data backed up, you can proceed without too much anxiety.
Also, when I did the first sync after clearing out Sync Services, I synced up each category of data one at a time, and I chose to overwrite my handheld with Entourage data the first time I synced.
After successfully syncing *everything*, I then tested out changing records in Entourage, and then synced again with success. Then, I changed a record on my Blackberry and synced again with success.
I hope this is helpful to everyone who is having frustrations with the sync process. I truly believe it has something to do w/ the communication between all the different databases becoming too complicated. Going through the above process will take any unnecessary information out of the picture and put a clean process in place.
Good luck!
p.s. I also posted this information in the MissingSync Forums