As many of you know there is a dumb bug that's been locking up the eBook Library when you plug in the USB into your PRS-505. I may have found a resolution. I used the computer's My Computer to do this. I moved all the books that are in <my drive letter>:\database\media\books to a folder on my computer. I put the USB back into my Reader and found I was now able to attach to the Library.
I pulled the USB and let the Reader startup. I saw there was something in my Purchased folder on the Reader. When I tried to access it the entire Reader crashed. So there was something in that particular area that was corrupt. I formatted the Reader altogether and then reattached to the Library software via USB and moved all my books back to the reader.
So, give it a try if you're having problems.
Good luck.