Not sure if this will fix issue or not. Go to your home settings (tap the "wheel" icon to get the settings drop down to appear. The 1st row or top section of the drop down box should be home settings, click on it)
In the home settings under active shelf there is a list of items to display. i.e. books, apps ,mags, etc. Look for one called documents and uncheck the box. Hopefully they will no longer appear in the active shelf.
I have also had my Nook HD+ for about a month. I had the same thing happen to me last week. I noticed my battery going down more quickly than normal, and then noticed the same icons on my home page. I took my Nook into the store, and talked with two of the staff members there. They had not heard of this before, nor did they have any idea where the files came from. We did end up getting the files deleted, and my battery is back to normal again. Just wanted to let you know this happened to someone else, as well.
Thanks for the suggestions...
Turns out the mystery files were coming from the Medscape application I downloaded. I guess the app automatically downloads new articles regularly and it had stored over 2,000 files onto my Nook. I deleted the app and found that the files were still there and had to go into my files and manually delete the Medscape folder in order to remove the files from my home screen.
Problem solved! Thanks again, anyways!