Adobe Digital Editions Update or Reinstall?

I'm was running ADE on a Win7 system.  Version 4.5.3.162045 kept prompting me to update and i kept saying I'll get around to it.  When I finally did, the update link was gone and if I load an overdrive book, it crashes.

Is there a way for me to update without uninstallng and reinstalling ADE, as my computer is already authorized?

Can I just download the latest version without unstalling 4.5.3?

And does the version 4.5.11 work on win7? 

Thanks for any help.