How long after I purchase the device will it go into this mode? What is this mode for? Is there any way around it so that I can add new files after it enters this mode?
flash memory has a limited life span. it is determined by how often it is written to or erased. the preserve only mode will activate when the device is nearing the end of the usable lifespan. this will allow you to read the pictures from the device (which has no impact on life span) but you cannot erase or write files to the device. i think sandisk can supply a tool that will unlock the device but if you do that it will eventually die.