As soon as I plug my USB cord (hooked up to the computer) into my Nook Tablet, it instantly shuts off. The computer doesn't recognized it as being hooked up, so I can't load my library books (via Adobe Digital Editions) or even access the NT in any way. When I unplug the USB cord, I have to do a hard re-start. I've tried two different B&N cables (we have a Nook Color also) as well as a cell phone cable. Nothing is working!
I can't even do a manual update of the latest firmware to see if that fixes it. I can connect via wi-fi, but haven't gotten the update yet. This just started today and I'm a HEAVY reader, so it's driving me crazy.
I hope you've resolved your problem by now. I had this problem on both of my Nook Tablets. I just took one into the store last week and they ended up replacing it.