ADE 3.0 Problems downloading ebooks

According to Barnes & Noble the only version I can use is the 3.0  On Dec 26 for some reason I couldn't download books.  I had to reload the 3.0 and then it was working alright.  Yesterday the .acsn file type was not in my defaults so I had to work with MIcrosoft to get that fixed but I still couldn't download my ebooks from my public library to digital editions.  I kept getting errors saying a previous version was detected and would I like to repair it.  I say yes and nothing happens.  Still can't download.  Normally I would get a downloaded file show up when I try downloading but that isn't happening so I don't know what in the world is going on.  I have removed everything and reloaded and reauthorized but nothing seems to work.  I worked with the chat people but now they say to get in touch with the forum.  Please help.