That was the second A-Data USB flash drive with 64 GB and this time were important data on it! Unfortunately, I'm going to stick to not send back, because important files were not meant for everyone so I'll have to destroy and forget the purchase price of the stick. So far, I was with the quality and reliability of A-Data Sticks (previously but only 16 GB) processed very satisfied, chic and high quality. Now meanwhile, is the second 64-GB flash drive after a few days no longer legible and that from now on the same, without any warning. Because no operating system is tuned, not Win, Mac still Ubuntu etc. The A-Data Online Restore does not help there! In short: This 64GB batch of A-Data is for a ton!