Error when returning library books

I am getting this error when I try to return a book in ADE v4.5.5 - Windows 10 x64

"Error returning item.  Please authorize your computer first"

But my computer is authorised..... (I mean how else would I have borrowed the book Adobe?)

Any thoughts on how to fix this error?  I am at my borrowing limit and want to get another book.

I have tried deleting authorisation and re-adding it.

Starting about 2 wks ago ADE 2.0.1.7  started crashing every time I tried to return a book. The program would close but the book had been returned to the library. The book would remain so I had to manually remove it from ADE. This was annoying but I could live with it. Today this same thing happened but now the books are no longer being returned to the library. I tried removing the book from ADE & download it again to see if I could get it to return. When I click on return I get  I get E_BAD_LOAN_ID. I have more than on library account & it is happening with both of them. I am running Win 8.1 & did try closing everything & restarting in case it was just a Win issue but that did nothing.

I spoke to the library & they referred me to Adobe. I did an online search & this issue does happen with other ADE versions.

The problem appears to have continued into ADE 3.0. I get E_BAD_LOAN_ID also. I downloaded the book with no ID so it is possible that this is the issue or maybe a part of it. I have since renewed my ID and I will try again. I just hate having a book "borrowed" that can not be returned and there fore can't be borrowed. I will make sure to let them know at Open Library so that they can reset things on their end. Thanks to all for the file locations so that I can clean things up on my pc.

The system tends to leave things around on your hard drive anyway;

you'll probably find all the (fairly small) .acsm files in your download directory as well as any left over .epub files in your Adobe directory.

Just delete the files from both when you are sure you are finished with them.

You may also find them still littering up any ereader you have.

v1.7.2 slightly less error prone than v2.0/2.0.1, but it will probably have many of the same problems.

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There are lots of bugs in ADE2.0 (and 2.0.1).  Try replacing ADE2.0 with the older but more reliable v1.7.2.

(You can have them both installed at once if you like.)

Version 1.7.2, it is a little difficult to find, available on Adobe site for Windows and for Mac.

http://helpx.adobe.com/digital-editions/kb/cant-install-digital-editions.html

The forum software is sometimes corrupting the link above.  There shouldn't be a blank in 'editio ns.html'.  The following redirects to the same page: http://tinyurl.com/diged172

Some people have found ADE trying to upgrade automatically. 

It appears (not 100% sure) that if you install ADE2.0 as a new install (not as an upgrade) that your 1.7.2 will continue to run.

Probably best to say no if 2.0.x installation asks if you want to migrate your library.