Thanks kovidgoyal, it all works now, though I'm not sure why. I initiated a formatting, got the message Formatting Internal Memory, then the reader froze completely. I left it over the night just in case a formatting really would take several hours. A reset this morning fixed the freeze with all my contents still intact on the reader, which means it can't have been formatted. But now at least calibre recognizes it, so I'm happy with that.
Thanks again, you're all very helpful.
|