OK, I am sure I did something to mess things up, so I am starting with a confession of guilt. Now on to the problem.
I downloaded an EPUB book, downloaded the Windows version of Adobe Digital Editions 4.5, logged into my Adobe account, and was able to access my book.
Then I wanted to transfer the book from my personal laptop to my work laptop, and set up an OverDrive account. Evidently big mistake.
Now, whether Digital Editions is authorized to my Adobe account or my OverDrive account, when I click on the book, it says that Authorization Needed, and it only allows me to input my Adobe account (not my OverDrive account info), followed by an error message "The vendor account you entered is not associated with the item you are trying to open. Try again."
So it would seem that the EPUB is tied to my OverDrive account, but Digital Editions will not allow me to enter my OverDrive account information when it is asking for authorization.
Your advice and input is appreciated. It is only a $10 EPUB, but this is quite aggrevating.