Well, uninstalled my Nook App and reinstalled. Still no go. Did a google search on error message and I see it's a problem that has happened before on Nook and it may right itself at some point.
I've never used Nook before so it was disheartening to attempt to download my first book on Nook (my own book no less) and see this error message. I thought it was personal error on my part during publishing but it seems to be a B&N issue.
Nevermind...I will wait and see what happens.
BTW--B&N did register my sale within 10 minutes, so that's a good thing.