PRS-T1 Cannot open books downloaded with Dropbox

Hi,

I had previously rooted my reader and used Dropbox without problems, but right now regardless of the Dropbox version I get the following error when trying to open the book:

Error

Contents cannot be found. They may have been moved or deleted.

To make this clear; the books are successfully downloaded to Dropbox's cache folder, but somehow the Reader app is not able to open them directly. If I browse to the cache in the file explorer I can open the with the Reader app.

I'm pretty sure it's really trying to open them with the Reader app, as I had reset file associations once and set it as the new default. Irregardless Ebook Downloader is also installed in my rooted reader, but doesn't work any better.

I haven't found any mention of this error on google and I've already re-rooted the reader without any success.

thanks,
Tim