I tried to launch the game a few times today. Each time I hit PLAY I got a black screen and an eventual Windows notice that ESO had failed to load. When trying to find the Repair option (which is not in launcher options for me that I can see) I noted the 64 bit toggle and turned it off. Voila, I got to the login screen.
Any suggestions on how I can regain 64 bit functionality? This is a new problem that has not affected me until now in a very long time using 64 bit.
(Possible factor that just occurred to me, I have the addon that helps expand memory use to avoid LUA errors,
http://www.esoui.com/downloads/info883-ShissusLUAMemory.html -- could that be a problem here? It's a newer addon for me but I have been using it a month or so without this launch failure until today).