And the lack of the functionality, that is, can't drag and drop any thumbnails is across the board. All of the PDF documents that I have are affected; some I've made from Word documents, some have been emailed to me. I've double checked the security on the documents, I've used specific PDF documents to test the functionality of moving thumbnails and rearranging them, etc. and, basically, what I've got is that when I click on a thumbnail and hold, it just does not drag or drop elsewhere in the thumbnail sequence.