Unable to add anything to library/software crashing

Hello,

I'm experiencing a lot of problems with ADE. Most recently I opened my ADE client after a while and noticed that there are no books in the library nor any of the bookshelves.

I wanted to add anything to library by this alert popped out

Problem is occuring with all the books that I have previously added sometime ago.

Next thing is that even if I plug in my Pocketbook reader to simply copy the books from device to computer, program is crashing.

I tried to re-install the software, but this never works.

How can I solve my problem?

Will be grateful for your help.