That may be a problem with the SD card, or the user may be locking files manually by tapping on the orange button which caused the SD card to get full of locked files and the unit stopped recording. The SD card must be formatted by Tapping Menu button once, Select General Settings, then scroll down and select "Format",  tap OK button, select the (O) to apply. That should fix the issue. If it doesn’t, then it would be necessary to try a new SD card.