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It is how to configure the advanced logging in Intellisync.
Once that is done, configure your syncing to ONLY sync the address book (you can reselect the others later).
Try a sync. Once that is complete, open the log files that were created. Somewhere near the end, you'll see the last contact (or at least enough info to discern the last contact) that it attempted to sync. Move this contact out of the address book and re-sync. If it competes, cool. Rebuild the offending contact. If it stalls again, repeat the process until the sync is successful. Usually web-based info has gotten into one of the fields and caused corruption.