Crisis: Evernote not working

This is all I see when I try to launch Evernote. I keep repeatedly trying it because maybe I didn't click the mouse right before or something. I upgraded through the App Store, and since then it just won't work. I deleted every crumb from my Mac and reinstalled, and then I deleted every crumb from THAT install and tried just dragging my backup over to my Mac, none of which worked. The folks at Evernote responded quickly to my desperate pleas for help, but they just suggested I reinstall. Obviously I would have tried that. I need to downgrade, but so far they've not responded to my requests. I'm having to use the Web interface, which although reassuring (my data still exist!), is annoying when I'm used to the real app fabulousness. Makes me reconsider the wisdom of relying so much on Evernote. Some folks are using Dropbox instead. I may look into it. Because this has totally killed me. It's eaten up like 6 hours of my life and still isn't working.