that generally means you have a corrupt file causing file syncing to hang. you can test by moving all your local synch files to a safe folder. retest syncing. if it works, move about 1/2 the files back to your sync folder. retest syncing. if it works, the culprit is in the other half. add 1/2 of them (or add them all to confirm the culprit's there). etc until you pinpoint the culprit or they all sync ok.