In Windows 8.1 Professional 64 Bit it happens again and again that the disc in a "sleep mode" is where it is no longer accessible. Have not found any settings that prevent this. Other discs run correctly, but does not lie on Windows.
After my review, the manufacturer has reported and meant for me, it could be due to an outdated firmware: Replaced and behold: All the best: Fast, small and until now reliable!