I get the same thing when I am just changing to another page. It encounters a problem and shuts down. I can have it re-start but when I go back to the page I was reading and then start to flip through the pages, it shuts down again!
Isn't therre any tech support out there from B&N to solve this issue??
I just tried something... I have dual monitors where I have my laptop and connected a second monitor. I moved the nook app to the remote monitor and this problem began. So, I moved the nook app back to my laptop and now it works and so far has not shut down.
If you have the nook application running on a remote monitor, that may be the cause. I will post again if I re-incounter this problem from my laptop.