That's odd. I know my FB requires a second password consisting of some code they text me when a new device seeks access to my account. It seems to always think my NSTG is a new device if I unsync and then resync (I was testing awhile back for the books that show at the bottom of the home screen).
But that process should be detailed clearly enough even on the NSTs limited browser ability.
Out of curiosity is the account linked and presenting an error, or is this a totally unlinked set up where entering the FB information generates the error?
If it's synced and giving an error- try unsyncing if you can and then resyncing.
If it's not synced at all then I doubt erasing and deregistering would work.
You may want to check your FB security settings as well.
It's not linked. I get the error message when I try to link it. I can use the FB app on the HD+, so FB isn't somehow blocking the device. Every time I try to link, I get an email from FB just noting that someone logged in from a new device--even though I've clicked on the OK from FB when I try to link. I've had the issue before--found my own posts when I did a search. That time, it cleared up possibly after accepting FB friends as Nook friends, but I think that was a co-incidence, as I've got that checked (even tried checking and unchecking.)
Oh no, not again! I was having this problem at the same time you were a few months ago. I tried everything on my NSTG, including de-registering (which didn't work) so don't try that. I also deleted the app in my FB account and that didn't work either. Then one day I just tried it again and it worked without doing anything different. I honestly think it is Facebook changing something in their code that is doing this. In fact, I just tried to post a "Like" on FB with my NSTG and I got an error too, so that tells me that it IS something on their end if others are having the same problem again. *sigh* What a bummer.
Others are posting on the Nook FB page that they are having the same problem. The Nook page just replied this morning that they are looking into it.
Facebook linking is working again tonight.
The fix went up yesterday afternoon after testing. Good to hear you are able to link again.