For some reason on one of my two 4500 displays when I remove the SD card to update the map database when I put the card back in and boot it does not see the database. I remove it and reload the database a few times and then finally works. Today I just removed the card after I saw the current database on the splash screen. When I put the card back in the slot the database was gone. Thinking it might be a bad card reader in the unit.