When transferring books from ADE to NOOK Color, copying funtion never stops

I used to be able to drag and drop books from ADE to my NOOK Color and it was fast and easy. Now, when I try to do that, or use the right click copy to device feature, ADE goes into "Copy" mode and never stops. I can't cancel out of it, nor can I close ADE....EXCEPT if I go to Task Manager and end tasks there. Oddly enough, the book is in my NOOK, but I'd like to fix this process error.