I have had the same problems as many others. Forced installation of Evernote 10.5.7 on my Windows desktop PC with notes then appearing blank in the reading pane and when opening individual notes, plus dialog boxes also blank. Closing ("X") Evernote didn't solve it, rebooting my PC usually did but only for a few hours. Tried uninstall and re-install.
Then found info on these forums which helped me to use Task Manager to kill processes, which fixed it some of the time. Also followed the advice to use File->Quit which works almost all the time.
But, having at least got back to the point of an application where I can actually read my notes, there are too many other changes that are horrible or annoying in 10.5.7. My laptop didn't force upgrade to 10.5.7 so I've been able to continue using "old" (working) Evernote on one machine. I then found info on here about reverting my PC to "Legacy" 6.25.2 Evernote - hallelujah!
I'm amazed a supposedly upgraded product has so many previous features missing, unusable changes and such a massive defect. Was there no user input, no user testing, no beta programme? I'll be sticking with Legacy V6.