Bought a new hard drive and working on copying over all my files. Almost done but now whenever I go to copy anything to the drive it just disappears. Doesn't show up under my computer, not under disk management. Just gone. Restarting the PC will bring it back but as soon as I try to copy to it it vanishes again. No idea what's going on with it. I can still go on it and navigate it and read from it but can't copy anything to it.