10.5.7 is doing strange things. If the Evernote app is open, I can be working in another app, and suddenly Evernote unexpectedly pops to the top of the window stack and the post-upgrade pop-up window (it may be the Release Notes pop-up window or a variation of it), displays on top of the Evernote window. Sometimes when I'm working in Evernote, that popup window appears unexpectedly.
I often go to open a Notebook and get the "Sorry, we're having some trouble" alert.
Evernote used to be so rock-solid. I'm very disappointed with this update.