This error typically occurs when there is a problem with the local file used to store information about your downloaded titles. To resolve this, please open [My] Computer or This PC and navigate to the location provided in the error message. By default, you'll find the file you need to edit here:
C:\Users\[your username]\AppData\Roaming\OverDrive\Media Console\
Select the file named MediaDB.dat and rename it to MediaDB.old. Afterward, you can close the window. OverDrive for Windows should now open successfully.