Clearing a task in a remote db does not clear it in the main db when synchronized, and vice versa. This leads to duplicate tasks (that require clearing in each db) and multiple history entries when cleared in each db. Is there a way to have the action of clearing a task in either the main or the remote update both?
It would help if you had provided mor specifics about your sync setup but I'm guessing that you are syncing between a home system adn an office system or between a laptop and a desktop system. If so, the likely source of your problem is having autorollover of activities turned on. As a general rule, auto rollover of activities shouldn't be used along with synchronization and definitely not in the enviroments I described.