iOS users take note: upgrading to iOS7 will affect your OverDrive experience.
If you have upgraded your iOS device to the new iOS7 released on Sept. 18, you will need to reauthenticate your OverDrive Media Console (OMC) app with a new or existing Adobe ID. You can follow the iOS section of this Help article  for assistance.
If that does not work, you should then uninstall and re-install the OMC app, which will also require you to re-authorize with Adobe. IMPORTANT NOTE: A re-install will clear your bookshelf, history, and app settings.
OverDrive assures us they are working on the issue, but in the meantime these two options should fix the issue.
If you do not follow these steps, the app will fail when trying to open a DRM-protected eBook.
Audiobook users won't notice that anything is different unless you attempt to download parts of audiobooks you already downloaded to OMC before upgrading to iOS 7. You will receive an error message informing you to download the title again.
If you have never installed or used OMC before upgrading to iOS 7, you will be unaffected by this issue.