Same here ... It started this morning after rebooting the desktop. I, too, can login to the website, but THAT simply tells me that my desktop client has not been loaded. It offers me a chance to download the same version I already have.
Is this issue (maybe) related to the other threads about the server being too busy (Error 7147)?
I really need this application to work, today in particular. Seems the gremlins always show up at the most inopportune times.
I'll forward an email to Seven, and see if they can help. Wish us luck.
OK, I fixed this on my machine ... I completely uninstalled the client, rebooted, removed a couple of remaining registry keys (did a search for Xpress Mail, and deleted two of the keys that showed up), and then reinstalled and rebooted. It all seems OK for now.
Note, I needed to re-register my device after all was done.