Both. Usually right away, but sometimes it will work for a few days before giving up the ghost. I bought new drives(can never have too many anyway) tried smaller size drives, formatted every system type, and switched from "quick removal" to "better performance." Same response. I wouldn't call myself advance computer literate by any stretch of the imagination, but still seems like this should be a non issue. Like CW said, hoping it has something to do with the extension but not holding my breath on that as the Avant 2 worked perfectly.