Error! Check Activation

I'm also having the Error! Check Activation message pop up after downloading the most updated version of Adobe Digital Editions and attempting to open ebooks. This also happens when selecting one of the sample ebooks provided on the Adobe website.

I have this problem too. I have been downloading epub books from my local public library (in the UK) for a couple of years with no problems but recently had to wipe the hard drive on my laptop and reinstall windows plus all other software including Digital Editions; now I get the Error! Check Activation message every time I try downloading a book - very frustrating!