Thanks for the info. I do a lot of editing and then I do a lot of backing up. From my main drive I copy to three others usint the computer, then to a folder on my computer, and then to my computer HD backup. ( I really don't want to lose all those editing hours ) I'm thinking the gliches are happening during the backup process and today have read that USBs do have a limitied useful life. Maybe time for some new ones.