During the HotFolder import the following error message is shown:
Unknown error while opening E:\ABBYY_HotFolder\.....122060.pdf
It is possible that the pdf file itself is corrupted.
Open the problematic pdf file in Acrobat Reader and scroll the pages down all the way to the last page. If during the scrolling and some error message occurs or the Acrobat Reader crashes, that means the pdf file is corrupted and FlexiCapture won't able to process the file as well.