I sync all my music successfully and then unplug

I sync all my music successfully and then unplug the player/device - it immediately starts updating library and then freezes during the process - a soft reset doesnt work -have to use the device manager to repair which results in all the music being deleted - have to go through the whole process of sync and again it freezes in the middle of updating library. Please note firmware is the latest/up to date battery fully charged.Help??????