You've probably already checked, but just in case...did you check your Device Info to see if you have run out of space for your B&N Content Storage? If you haven't had your NC repartitioned at a B&N store, you may need to.
I do have space but I've never heard of repartitioning- what is that? I did the deregister/reregister thing yesterday after I posted and am having the same problem. Should I go into B&N and see if they can fix it? I don't know what else to do.
I had the same problem, read the posts and went to a B&N store in search of a repartition. But, it turns out that wasn't the problem. Apparently something interupted the downloads of the apps I was having problems with. The fix - archive the app, power off the Nook for at least 30 seconds, power up and reinstall.
Although I don't sideload hardly anything, I'm not ready to repartition my drive when I still have a boat load of available memory. I'll keep that for another day in the future.
I had the same problem (apps would appear to download but then get stalled in a download/install/download/install loop) and here are the steps they took in the store to solve the issue. I could have done this at home if I'd known . . .
1. Archive all apps
2. Copy any sideloaded material to your computer
3. Deregister your nook
4. Log into your account on bn.com
5. Unarchive all apps
6. Re-register your nook
7. Wait for all apps to show up
8. Download each app
This worked for me. Before this I had tried the same thing except I unarchived the apps via the nook, rather than logging into my account on bn.com. Not sure why that made a difference, but it did.