Connection Error Detected

I have been trying to download the latest version of Digital Editions and it isn't working at all so I downgraded to version 3.0 and it at least let me authorize the computer.  Now I'm getting  the above Connection Error Detected when I try to download a book from the library. The rest of it says Digital Editions could not connect to the fulfillment center. Please make sure that you are connected to the internet.  Well I am connected to the internet.  Anyone have any suggestions what to try??? I'm getting so frustrated with this Digital Editions stuff that I might take my sister's advice and return the Nook and buy a Kindle so that I don't have to use any other software to use as a go between to check out books from the library.