I have a WD External Hard drive. I've used it for years on both windows 7 & 8 computers. I believe when updated to 8.1 that started having issues. Only with the 8.1 computer. I can be in the middle of using it, or idle, and it says' "unknown usb device has stopped working". The light is still on the external, and it is still spinning, but it not longer shows up in my computer or in devices to eject. It is a 3.0, and I have tried both 3.0 ports, 2.0 ports, 3.0 hub. Also tried uninstalling drivers. Any other ideas? I don't think it's the drive b/c it still works perfectly on my other windows 7 computer. It is also not the "power saving" issue b/c it's a desktop and it happens when I'm in the middle of using it. This has been driving me crazy for months. Thanks!