its basically a sign that says your hard drive is about to take a dump. your going to have to fix the usb connection by soldering it and then extracting the files if you can off the hard drive onto you comp or laptop. once you have backed up your files from the external hardrive then you will have to repair and reformat the disk drive and hopefully that will fix it and then reload or back up your files onto the external hard drive. you will notice that on your computer you will get a notification saying that your computer could not be backed up. if so then redo the process.