Something I would check but can't guartantee will fix your issue:
1) On a desktop computer login to your Gmail account
2) Click on the cogwheel top right
3) click Settings
4) click on the tab labeled "Forwarding and POP/IMAP"
5) make sure IMAP is enabled
6) click "Configuration Instructions"
7) click "Android"
8) make sure the settings match what is set in the Email App on your Nook
good luck to you
Thank you; I just checked all you suggested and it is all set up as you described. The thing is that the email app worked properly for many months before this happened. It happened spontaneously and when they did the factory reset, it worked properly again for a short time before it started to again "stop working unexpectedly and Force Close" on me. I don't think it's the server or my provider, but the App itself, or the device's configuration which is preprogrammed. I cannot delete and reinstall the email app. sigh
Have you tried the K9 email app which is available free in the B&N app store? I have used the Android version on an NC running CM7 and found it much better than the stock app.