Same issue for me and many others
I had version 1.7 (win 7, 64bit) working fine until this morning. Books downloaded ok from both local library using overdrive and school library using EBL. Then one *.ascm file failed to load citing an IO error on network request.
I followed the instructions at OverDrive | What to do if there is an "IO Error... and this didn't work. Same error still appeared.
Next tried upgrading to most recent version of Digital Editions, which migrated in my borrowed books and my authorisation okay. Tried clearing cache and ensuring every adblock etc still turned off, redownloaded the *.ascm and got a new Check! Activation error....
I removed my authorisation, then closed, reopened and reauthorised and then cleared files as per Overdrive link above... now getting
Unable to download
Error getting licence. Licence server communication problem.
Occurs with book PDF and ePub versions of the *.ascm and is very frustrating!
Okay, so no on a different error...
My understanding is this is an error with the password going from EBL to Adobe as part of token fulfillment. Other books working ok so I believe it is an issue with this individual book and have reported it to EBL.