If you experience this it may be the case that the USB Flash Drive file table may have become corrupted or damaged. You will need to format the Flash Drive to re-use it. Firstly, ensure you have no important data stored on the Flash Drive. If you are concerned about the loss of some important data files, contact Integral Tech Support before formatting. If you are unable to format the Integral Flash Drive then fill in the tech support form and we can assist you further.