[bobcdy]

I've had a similar problem - my Nook ST developed an objection to my sd card. Sometimes it worked ok, other times it won't detect card until I remove the card and reinsert it. Tried another card, reformatted it with SDFormatter, also tried reformatting with the Nook. Tried a class 10 card but no better luck. Sometimes ok, other times can't find the sd card, or it detects a card but wants to format it - after reformatting the same problem occurs. Oddly once it is has recognized a card, it will work fine (can choose other ebooks after starting with one, and read for hours) until it is turned off. Then it is erratic. It's out of warranty, so I purchased a refurb from ebay and that works ok. I'm keeping the problem device because it does work after a fashion and is ok as a backup.

I've never found that the Nook corrupts the ebooks during detection problems; if I remove the card from the problem nook and use it in the refurb., all books are accessible and readable.